merge development

72 files changed, 1683 insertions, 493 deletions

diff --git a/packages/contracts/README.md b/packages/contracts/README.md
index 2e6376f39..33cbdae26 100644
--- a/packages/contracts/README.md
+++ b/packages/contracts/README.md
@@ -1,14 +1,35 @@
 ## Contracts
 
-Smart contracts that implement the 0x protocol.
+Smart contracts that implement the 0x protocol. Addresses of the deployed contracts can be found [here](https://0xproject.com/wiki#Deployed-Addresses).
 
 ## Usage
 
-*   [Docs](https://0xproject.com/docs/contracts)
-*   [Overview of 0x protocol architecture](https://0xproject.com/wiki#Architecture)
-*   [0x smart contract interactions](https://0xproject.com/wiki#Contract-Interactions)
-*   [Deployed smart contract addresses](https://0xproject.com/wiki#Deployed-Addresses)
-*   [0x protocol message format](https://0xproject.com/wiki#Message-Format)
+### 2.0.0
+
+Contracts that make up and interact with version 2.0.0 of the protocol can be found in the `src/2.0.0` directory. The contents of this directory are broken down into the following subdirectories:
+
+*   protocol
+    *   This directory contains the contracts that make up version 2.0.0. A full specification can be found [here](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md).
+*   extensions
+    *   This directory contains contracts that interact with the 2.0.0 contracts and will be used in production, such as the [Forwarder](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/forwarder-specification.md) contract.
+*   examples
+    *   This directory contains example implementations of contracts that interact with the protocol but are _not_ intended for use in production. Examples include [filter](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#filter-contracts) contracts, a [Wallet](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#wallet) contract, and a [Validator](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md#validator) contract, among others.
+*   tokens
+    *   This directory contains implementations of different tokens and token standards, including [wETH](https://weth.io/), ZRX, [ERC20](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md), and [ERC721](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md).
+*   multisig
+    *   This directory contains the [Gnosis MultiSigWallet](https://github.com/gnosis/MultiSigWallet) and a custom extension that adds a timelock to transactions within the MultiSigWallet.
+*   utils
+    *   This directory contains libraries and utils that are shared across all of the other directories.
+*   test
+    *   This directory contains mocks and other contracts that are used solely for testing contracts within the other directories.
+
+### 1.0.0
+
+Contracts that make up version 1.0.0 of the protocol can be found in `src/1.0.0`. These contracts are considered deprecated and will have limited support going forward.
+
+## Bug bounty
+
+A bug bounty for the 2.0.0 contracts is ongoing! Instructions can be found [here](https://0xproject.com/wiki#Bug-Bounty).
 
 ## Contributing
 
diff --git a/packages/contracts/compiler.json b/packages/contracts/compiler.json
index f66114e87..559b7cd1f 100644
--- a/packages/contracts/compiler.json
+++ b/packages/contracts/compiler.json
@@ -1,5 +1,5 @@
 {
-    "artifactsDir": "../migrations/artifacts/2.0.0",
+    "artifactsDir": "../migrations/artifacts/development",
     "contractsDir": "src/",
     "compilerSettings": {
         "optimizer": {
@@ -23,6 +23,7 @@
         "DummyERC20Token",
         "DummyERC721Receiver",
         "DummyERC721Token",
+        "DummyMultipleReturnERC20Token",
         "DummyNoReturnERC20Token",
         "ERC20Proxy",
         "ERC20Token",
diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index 5d2f290ac..5cc239ae7 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -1,7 +1,7 @@
 {
     "private": true,
     "name": "contracts",
-    "version": "2.1.42",
+    "version": "2.1.47",
     "engines": {
         "node": ">=6.12"
     },
@@ -11,10 +11,9 @@
         "test": "test"
     },
     "scripts": {
-        "watch_without_deps": "yarn pre_build && tsc -w",
-        "build": "yarn pre_build && tsc",
+        "build": "yarn pre_build && tsc -b",
         "pre_build": "run-s compile copy_artifacts generate_contract_wrappers",
-        "copy_artifacts": "copyfiles -u 4 '../migrations/artifacts/2.0.0/**/*' ./lib/artifacts;",
+        "copy_artifacts": "copyfiles -u 4 '../migrations/artifacts/development/**/*' ./lib/artifacts;",
         "test": "yarn run_mocha",
         "rebuild_and_test": "run-s build test",
         "test:coverage": "SOLIDITY_COVERAGE=true run-s build run_mocha coverage:report:text coverage:report:lcov",
@@ -33,7 +32,7 @@
         "lint-contracts": "solhint src/2.0.0/**/**/**/**/*.sol"
     },
     "config": {
-        "abis": "../migrations/artifacts/2.0.0/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|DummyNoReturnERC20Token|ERC20Proxy|ERC721Proxy|Forwarder|Exchange|ExchangeWrapper|IAssetData|IAssetProxy|InvalidERC721Receiver|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|OrderValidator|ReentrantERC20Token|TestAssetProxyOwner|TestAssetProxyDispatcher|TestConstants|TestExchangeInternals|TestLibBytes|TestLibs|TestSignatureValidator|TestStaticCallReceiver|Validator|Wallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
+        "abis": "../migrations/artifacts/development/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|DummyMultipleReturnERC20Token|DummyNoReturnERC20Token|ERC20Proxy|ERC721Proxy|Forwarder|Exchange|ExchangeWrapper|IAssetData|IAssetProxy|InvalidERC721Receiver|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|OrderValidator|ReentrantERC20Token|TestAssetProxyOwner|TestAssetProxyDispatcher|TestConstants|TestExchangeInternals|TestLibBytes|TestLibs|TestSignatureValidator|TestStaticCallReceiver|Validator|Wallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
     },
     "repository": {
         "type": "git",
@@ -46,16 +45,16 @@
     },
     "homepage": "https://github.com/0xProject/0x-monorepo/packages/contracts/README.md",
     "devDependencies": {
-        "@0xproject/abi-gen": "^1.0.7",
-        "@0xproject/dev-utils": "^1.0.6",
-        "@0xproject/sol-compiler": "^1.1.1",
-        "@0xproject/sol-cov": "^2.1.1",
-        "@0xproject/subproviders": "^2.0.1",
-        "@0xproject/tslint-config": "^1.0.6",
+        "@0xproject/abi-gen": "^1.0.11",
+        "@0xproject/dev-utils": "^1.0.10",
+        "@0xproject/sol-compiler": "^1.1.5",
+        "@0xproject/sol-cov": "^2.1.5",
+        "@0xproject/subproviders": "^2.0.5",
+        "@0xproject/tslint-config": "^1.0.7",
         "@types/bn.js": "^4.11.0",
         "@types/ethereumjs-abi": "^0.6.0",
         "@types/lodash": "4.14.104",
-        "@types/node": "^8.0.53",
+        "@types/node": "*",
         "@types/yargs": "^10.0.0",
         "chai": "^4.0.1",
         "chai-as-promised": "^7.1.0",
@@ -73,18 +72,18 @@
         "yargs": "^10.0.3"
     },
     "dependencies": {
-        "@0xproject/base-contract": "^2.0.1",
-        "@0xproject/order-utils": "^1.0.1-rc.6",
-        "@0xproject/types": "^1.0.1-rc.6",
-        "@0xproject/typescript-typings": "^1.0.5",
-        "@0xproject/utils": "^1.0.7",
-        "@0xproject/web3-wrapper": "^2.0.1",
+        "@0xproject/base-contract": "^2.0.5",
+        "@0xproject/order-utils": "^1.0.5",
+        "@0xproject/types": "^1.1.1",
+        "@0xproject/typescript-typings": "^2.0.2",
+        "@0xproject/utils": "^1.0.11",
+        "@0xproject/web3-wrapper": "^3.0.1",
         "@types/js-combinatorics": "^0.5.29",
         "bn.js": "^4.11.8",
-        "ethereum-types": "^1.0.5",
+        "ethereum-types": "^1.0.8",
         "ethereumjs-abi": "0.6.5",
         "ethereumjs-util": "^5.1.1",
-        "ethers": "3.0.22",
+        "ethers": "4.0.0-beta.14",
         "js-combinatorics": "^0.5.3",
         "lodash": "^4.17.5"
     }
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
index 6b17bb29b..94dec40ed 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
@@ -34,7 +34,6 @@ contract Forwarder is
     MixinExchangeWrapper,
     MixinForwarderCore
 {
-
     constructor (
         address _exchange,
         bytes memory _zrxAssetData,
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
index d6a38aa6e..43efb5ff3 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
@@ -31,7 +31,6 @@ contract MixinAssets is
     LibConstants,
     MAssets
 {
-
     using LibBytes for bytes;
 
     bytes4 constant internal ERC20_TRANSFER_SELECTOR = bytes4(keccak256("transfer(address,uint256)"));
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
index 9e816716c..fea9a53c2 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
@@ -34,7 +34,6 @@ contract MixinExchangeWrapper is
     LibConstants,
     MExchangeWrapper
 {
-
     /// @dev Fills the input order.
     ///      Returns false if the transaction would otherwise revert.
     /// @param order Order struct containing order specifications.
@@ -61,7 +60,7 @@ contract MixinExchangeWrapper is
         // Call `fillOrder` and handle any exceptions gracefully
         assembly {
             let success := call(
-                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                gas,                                // forward all gas
                 exchange,                           // call address of Exchange contract
                 0,                                  // transfer 0 wei
                 add(fillOrderCalldata, 32),         // pointer to start of input (skip array length in first 32 bytes)
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
index 14f191879..54487f726 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
@@ -39,7 +39,6 @@ contract MixinForwarderCore is
     MExchangeWrapper,
     IForwarderCore
 {
-
     using LibBytes for bytes;
 
     /// @dev Constructor approves ERC20 proxy to transfer ZRX and WETH on this contract's behalf.
@@ -47,10 +46,12 @@ contract MixinForwarderCore is
         public
     {
         address proxyAddress = EXCHANGE.getAssetProxy(ERC20_DATA_ID);
-        if (proxyAddress != address(0)) {
-            ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
-            ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
-        }
+        require(
+            proxyAddress != address(0),
+            "UNREGISTERED_ASSET_PROXY"
+        );
+        ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
+        ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
     }
 
     /// @dev Purchases as much of orders' makerAssets as possible by selling up to 95% of transaction's ETH value.
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
index 5863b522d..d2814a49b 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
@@ -28,7 +28,6 @@ contract MixinWeth is
     LibConstants,
     MWeth
 {
-
     /// @dev Default payabale function, this allows us to withdraw WETH
     function ()
         public
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
index 83636432a..9e7f80d97 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAssets.sol";
 contract MAssets is
     IAssets
 {
-
     /// @dev Transfers given amount of asset to sender.
     /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param amount Amount of asset to transfer to sender.
diff --git a/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
index a18345245..8bfde3847 100644
--- a/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
+++ b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
@@ -28,11 +28,11 @@ import "../../utils/LibBytes/LibBytes.sol";
 
 contract OrderValidator {
 
+    using LibBytes for bytes;
+
     bytes4 constant internal ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
     bytes4 constant internal ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256)"));
 
-    using LibBytes for bytes;
-
     struct TraderInfo {
         uint256 makerBalance;       // Maker's balance of makerAsset
         uint256 makerAllowance;     // Maker's allowance to corresponding AssetProxy
diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
index eb54fe047..516e7391c 100644
--- a/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
@@ -1,13 +1,14 @@
 // solhint-disable
-pragma solidity ^0.4.10;
+pragma solidity ^0.4.15;
 
 
 /// @title Multisignature wallet - Allows multiple parties to agree on transactions before execution.
 /// @author Stefan George - <stefan.george@consensys.net>
 contract MultiSigWallet {
 
-    uint constant public MAX_OWNER_COUNT = 50;
-
+    /*
+     *  Events
+     */
     event Confirmation(address indexed sender, uint indexed transactionId);
     event Revocation(address indexed sender, uint indexed transactionId);
     event Submission(uint indexed transactionId);
@@ -18,6 +19,14 @@ contract MultiSigWallet {
     event OwnerRemoval(address indexed owner);
     event RequirementChange(uint required);
 
+    /*
+     *  Constants
+     */
+    uint constant public MAX_OWNER_COUNT = 50;
+
+    /*
+     *  Storage
+     */
     mapping (uint => Transaction) public transactions;
     mapping (uint => mapping (address => bool)) public confirmations;
     mapping (address => bool) public isOwner;
@@ -32,60 +41,54 @@ contract MultiSigWallet {
         bool executed;
     }
 
+    /*
+     *  Modifiers
+     */
     modifier onlyWallet() {
-        if (msg.sender != address(this))
-            throw;
+        require(msg.sender == address(this));
         _;
     }
 
     modifier ownerDoesNotExist(address owner) {
-        if (isOwner[owner])
-            throw;
+        require(!isOwner[owner]);
         _;
     }
 
     modifier ownerExists(address owner) {
-        if (!isOwner[owner])
-            throw;
+        require(isOwner[owner]);
         _;
     }
 
     modifier transactionExists(uint transactionId) {
-        if (transactions[transactionId].destination == 0)
-            throw;
+        require(transactions[transactionId].destination != 0);
         _;
     }
 
     modifier confirmed(uint transactionId, address owner) {
-        if (!confirmations[transactionId][owner])
-            throw;
+        require(confirmations[transactionId][owner]);
         _;
     }
 
     modifier notConfirmed(uint transactionId, address owner) {
-        if (confirmations[transactionId][owner])
-            throw;
+        require(!confirmations[transactionId][owner]);
         _;
     }
 
     modifier notExecuted(uint transactionId) {
-        if (transactions[transactionId].executed)
-            throw;
+        require(!transactions[transactionId].executed);
         _;
     }
 
     modifier notNull(address _address) {
-        if (_address == 0)
-            throw;
+        require(_address != 0);
         _;
     }
 
     modifier validRequirement(uint ownerCount, uint _required) {
-        if (   ownerCount > MAX_OWNER_COUNT
-            || _required > ownerCount
-            || _required == 0
-            || ownerCount == 0)
-            throw;
+        require(ownerCount <= MAX_OWNER_COUNT
+            && _required <= ownerCount
+            && _required != 0
+            && ownerCount != 0);
         _;
     }
 
@@ -108,8 +111,7 @@ contract MultiSigWallet {
         validRequirement(_owners.length, _required)
     {
         for (uint i=0; i<_owners.length; i++) {
-            if (isOwner[_owners[i]] || _owners[i] == 0)
-                throw;
+            require(!isOwner[_owners[i]] && _owners[i] != 0);
             isOwner[_owners[i]] = true;
         }
         owners = _owners;
@@ -151,7 +153,7 @@ contract MultiSigWallet {
 
     /// @dev Allows to replace an owner with a new owner. Transaction has to be sent by wallet.
     /// @param owner Address of owner to be replaced.
-    /// @param owner Address of new owner.
+    /// @param newOwner Address of new owner.
     function replaceOwner(address owner, address newOwner)
         public
         onlyWallet
@@ -222,20 +224,44 @@ contract MultiSigWallet {
     /// @param transactionId Transaction ID.
     function executeTransaction(uint transactionId)
         public
+        ownerExists(msg.sender)
+        confirmed(transactionId, msg.sender)
         notExecuted(transactionId)
     {
         if (isConfirmed(transactionId)) {
-            Transaction tx = transactions[transactionId];
-            tx.executed = true;
-            if (tx.destination.call.value(tx.value)(tx.data))
+            Transaction storage txn = transactions[transactionId];
+            txn.executed = true;
+            if (external_call(txn.destination, txn.value, txn.data.length, txn.data))
                 Execution(transactionId);
             else {
                 ExecutionFailure(transactionId);
-                tx.executed = false;
+                txn.executed = false;
             }
         }
     }
 
+    // call has been separated into its own function in order to take advantage
+    // of the Solidity's code generator to produce a loop that copies tx.data into memory.
+    function external_call(address destination, uint value, uint dataLength, bytes data) internal returns (bool) {
+        bool result;
+        assembly {
+            let x := mload(0x40)   // "Allocate" memory for output (0x40 is where "free memory" pointer is stored by convention)
+            let d := add(data, 32) // First 32 bytes are the padded length of data, so exclude that
+            result := call(
+                sub(gas, 34710),   // 34710 is the value that solidity is currently emitting
+                                   // It includes callGas (700) + callVeryLow (3, to pay for SUB) + callValueTransferGas (9000) +
+                                   // callNewAccountGas (25000, in case the destination address does not exist and needs creating)
+                destination,
+                value,
+                d,
+                dataLength,        // Size of the input (in bytes) - this is what fixes the padding problem
+                x,
+                0                  // Output is ignored, therefore the output size is zero
+            )
+        }
+        return result;
+    }
+
     /// @dev Returns the confirmation status of a transaction.
     /// @param transactionId Transaction ID.
     /// @return Confirmation status.
@@ -364,4 +390,4 @@ contract MultiSigWallet {
         for (i=from; i<to; i++)
             _transactionIds[i - from] = transactionIdsTemp[i];
     }
-}
+}
\ No newline at end of file
diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
index 8c5e6e1e6..9513d3b30 100644
--- a/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
@@ -16,47 +16,57 @@
 
 */
 
-// solhint-disable
-pragma solidity ^0.4.10;
+pragma solidity 0.4.24;
 
 import "./MultiSigWallet.sol";
 
 
 /// @title Multisignature wallet with time lock- Allows multiple parties to execute a transaction after a time lock has passed.
 /// @author Amir Bandeali - <amir@0xProject.com>
-contract MultiSigWalletWithTimeLock is MultiSigWallet {
-
-    event ConfirmationTimeSet(uint indexed transactionId, uint confirmationTime);
-    event TimeLockChange(uint secondsTimeLocked);
-
-    uint public secondsTimeLocked;
-
-    mapping (uint => uint) public confirmationTimes;
-
-    modifier notFullyConfirmed(uint transactionId) {
-        require(!isConfirmed(transactionId));
+// solhint-disable not-rely-on-time
+contract MultiSigWalletWithTimeLock is
+    MultiSigWallet
+{
+    event ConfirmationTimeSet(uint256 indexed transactionId, uint256 confirmationTime);
+    event TimeLockChange(uint256 secondsTimeLocked);
+
+    uint256 public secondsTimeLocked;
+
+    mapping (uint256 => uint256) public confirmationTimes;
+
+    modifier notFullyConfirmed(uint256 transactionId) {
+        require(
+            !isConfirmed(transactionId),
+            "TX_FULLY_CONFIRMED"
+        );
         _;
     }
 
-    modifier fullyConfirmed(uint transactionId) {
-        require(isConfirmed(transactionId));
+    modifier fullyConfirmed(uint256 transactionId) {
+        require(
+            isConfirmed(transactionId),
+            "TX_NOT_FULLY_CONFIRMED"
+        );
         _;
     }
 
-    modifier pastTimeLock(uint transactionId) {
-        require(block.timestamp >= confirmationTimes[transactionId] + secondsTimeLocked);
+    modifier pastTimeLock(uint256 transactionId) {
+        require(
+            block.timestamp >= confirmationTimes[transactionId] + secondsTimeLocked,
+            "TIME_LOCK_INCOMPLETE"
+        );
         _;
     }
 
-    /*
-     * Public functions
-     */
-
     /// @dev Contract constructor sets initial owners, required number of confirmations, and time lock.
     /// @param _owners List of initial owners.
     /// @param _required Number of required confirmations.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function MultiSigWalletWithTimeLock(address[] _owners, uint _required, uint _secondsTimeLocked)
+    constructor (
+        address[] _owners,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
         public
         MultiSigWallet(_owners, _required)
     {
@@ -65,17 +75,17 @@ contract MultiSigWalletWithTimeLock is MultiSigWallet {
 
     /// @dev Changes the duration of the time lock for transactions.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function changeTimeLock(uint _secondsTimeLocked)
+    function changeTimeLock(uint256 _secondsTimeLocked)
         public
         onlyWallet
     {
         secondsTimeLocked = _secondsTimeLocked;
-        TimeLockChange(_secondsTimeLocked);
+        emit TimeLockChange(_secondsTimeLocked);
     }
 
     /// @dev Allows an owner to confirm a transaction.
     /// @param transactionId Transaction ID.
-    function confirmTransaction(uint transactionId)
+    function confirmTransaction(uint256 transactionId)
         public
         ownerExists(msg.sender)
         transactionExists(transactionId)
@@ -83,52 +93,35 @@ contract MultiSigWalletWithTimeLock is MultiSigWallet {
         notFullyConfirmed(transactionId)
     {
         confirmations[transactionId][msg.sender] = true;
-        Confirmation(msg.sender, transactionId);
+        emit Confirmation(msg.sender, transactionId);
         if (isConfirmed(transactionId)) {
             setConfirmationTime(transactionId, block.timestamp);
         }
     }
 
-    /// @dev Allows an owner to revoke a confirmation for a transaction.
-    /// @param transactionId Transaction ID.
-    function revokeConfirmation(uint transactionId)
-        public
-        ownerExists(msg.sender)
-        confirmed(transactionId, msg.sender)
-        notExecuted(transactionId)
-        notFullyConfirmed(transactionId)
-    {
-        confirmations[transactionId][msg.sender] = false;
-        Revocation(msg.sender, transactionId);
-    }
-
     /// @dev Allows anyone to execute a confirmed transaction.
     /// @param transactionId Transaction ID.
-    function executeTransaction(uint transactionId)
+    function executeTransaction(uint256 transactionId)
         public
         notExecuted(transactionId)
         fullyConfirmed(transactionId)
         pastTimeLock(transactionId)
     {
-        Transaction storage tx = transactions[transactionId];
-        tx.executed = true;
-        if (tx.destination.call.value(tx.value)(tx.data))
-            Execution(transactionId);
-        else {
-            ExecutionFailure(transactionId);
-            tx.executed = false;
+        Transaction storage txn = transactions[transactionId];
+        txn.executed = true;
+        if (external_call(txn.destination, txn.value, txn.data.length, txn.data)) {
+            emit Execution(transactionId);
+        } else {
+            emit ExecutionFailure(transactionId);
+            txn.executed = false;
         }
     }
 
-    /*
-     * Internal functions
-     */
-
     /// @dev Sets the time of when a submission first passed.
-    function setConfirmationTime(uint transactionId, uint confirmationTime)
+    function setConfirmationTime(uint256 transactionId, uint256 confirmationTime)
         internal
     {
         confirmationTimes[transactionId] = confirmationTime;
-        ConfirmationTimeSet(transactionId, confirmationTime);
+        emit ConfirmationTimeSet(transactionId, confirmationTime);
     }
 }
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
index 004c3892d..258443bca 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
@@ -18,7 +18,6 @@
 
 pragma solidity 0.4.24;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./MixinAuthorizable.sol";
 
 
@@ -59,15 +58,64 @@ contract ERC20Proxy is
                     mstore(96, 0)
                     revert(0, 100)
                 }
-                
-                /////// Token contract address ///////
-                // The token address is found as follows:
-                // * It is stored at offset 4 in `assetData` contents.
-                // * This is stored at offset 32 from `assetData`.
-                // * The offset to `assetData` from Params is stored at offset
-                //   4 in calldata.
-                // * The offset of Params in calldata is 4.
-                // So we read location 4 and add 32 + 4 + 4 to it.
+
+                // `transferFrom`.
+                // The function is marked `external`, so no abi decodeding is done for
+                // us. Instead, we expect the `calldata` memory to contain the
+                // following:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. offset to assetData (*)        |
+                // |          | 36     |         |   2. from                           |
+                // |          | 68     |         |   3. to                             |
+                // |          | 100    |         |   4. amount                         |
+                // | Data     |        |         | assetData:                          |
+                // |          | 132    | 32      | assetData Length                    |
+                // |          | 164    | **      | assetData Contents                  |
+                //
+                // (*): offset is computed from start of function parameters, so offset
+                //      by an additional 4 bytes in the calldata.
+                //
+                // (**): see table below to compute length of assetData Contents
+                //
+                // WARNING: The ABIv2 specification allows additional padding between
+                //          the Params and Data section. This will result in a larger
+                //          offset to assetData.
+
+                // Asset data itself is encoded as follows:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 1 * 32  | function parameters:                |
+                // |          | 4      | 12 + 20 |   1. token address                  |
+
+                // We construct calldata for the `token.transferFrom` ABI.
+                // The layout of this calldata is in the table below.
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 3 * 32  | function parameters:                |
+                // |          | 4      |         |   1. from                           |
+                // |          | 36     |         |   2. to                             |
+                // |          | 68     |         |   3. amount                         |
+
+                /////// Read token address from calldata ///////
+                // * The token address is stored in `assetData`.
+                //
+                // * The "offset to assetData" is stored at offset 4 in the calldata (table 1).
+                //   [assetDataOffsetFromParams = calldataload(4)]
+                //
+                // * Notes that the "offset to assetData" is relative to the "Params" area of calldata;
+                //   add 4 bytes to account for the length of the "Header" area (table 1).
+                //   [assetDataOffsetFromHeader = assetDataOffsetFromParams + 4]
+                //
+                // * The "token address" is offset 32+4=36 bytes into "assetData" (tables 1 & 2).
+                //   [tokenOffset = assetDataOffsetFromHeader + 36 = calldataload(4) + 4 + 36]
                 let token := calldataload(add(calldataload(4), 40))
                 
                 /////// Setup Header Area ///////
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
index 9d0bc0f74..65b664b8b 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -18,7 +18,6 @@
 
 pragma solidity 0.4.24;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./MixinAuthorizable.sol";
 
 
@@ -80,6 +79,8 @@ contract ERC721Proxy is
                 // (*): offset is computed from start of function parameters, so offset
                 //      by an additional 4 bytes in the calldata.
                 //
+                // (**): see table below to compute length of assetData Contents
+                //
                 // WARNING: The ABIv2 specification allows additional padding between
                 //          the Params and Data section. This will result in a larger
                 //          offset to assetData.
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
index ff4660a31..fe9bbf848 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
@@ -26,7 +26,6 @@ contract MixinAuthorizable is
     Ownable,
     MAuthorizable
 {
-
     /// @dev Only authorized addresses can invoke functions with this modifier.
     modifier onlyAuthorized {
         require(
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
index 3651dd694..b25d2d75a 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -24,7 +24,6 @@ import "./IAuthorizable.sol";
 contract IAssetProxy is
     IAuthorizable
 {
-
     /// @dev Transfers assets. Either succeeds or throws.
     /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer asset from.
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
index 8fac43a47..ba1d4aa77 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
@@ -24,7 +24,6 @@ import "../../../utils/Ownable/IOwnable.sol";
 contract IAuthorizable is
     IOwnable
 {
-
     /// @dev Authorizes an address.
     /// @param target Address to authorize.
     function addAuthorizedAddress(address target)
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
index 8afc8c8d8..d63fb7f6d 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAuthorizable.sol";
 contract MAuthorizable is
     IAuthorizable
 {
-
     // Event logged when a new address is authorized.
     event AuthorizedAddressAdded(
         address indexed target,
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
index 8b7333646..edb788fab 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
@@ -16,14 +16,16 @@
 
 */
 
-pragma solidity 0.4.10;
+pragma solidity 0.4.24;
 
 import "../../multisig/MultiSigWalletWithTimeLock.sol";
+import "../../utils/LibBytes/LibBytes.sol";
 
 
 contract AssetProxyOwner is
     MultiSigWalletWithTimeLock
 {
+    using LibBytes for bytes;
 
     event AssetProxyRegistration(address assetProxyContract, bool isRegistered);
 
@@ -36,9 +38,15 @@ contract AssetProxyOwner is
     /// @dev Function will revert if the transaction does not call `removeAuthorizedAddressAtIndex`
     ///      on an approved AssetProxy contract.
     modifier validRemoveAuthorizedAddressAtIndexTx(uint256 transactionId) {
-        Transaction storage tx = transactions[transactionId];
-        require(isAssetProxyRegistered[tx.destination]);
-        require(readBytes4(tx.data, 0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR);
+        Transaction storage txn = transactions[transactionId];
+        require(
+            isAssetProxyRegistered[txn.destination],
+            "UNREGISTERED_ASSET_PROXY"
+        );
+        require(
+            txn.data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR,
+            "INVALID_FUNCTION_SELECTOR"
+        );
         _;
     }
 
@@ -48,7 +56,7 @@ contract AssetProxyOwner is
     /// @param _assetProxyContracts Array of AssetProxy contract addresses.
     /// @param _required Number of required confirmations.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function AssetProxyOwner(
+    constructor (
         address[] memory _owners,
         address[] memory _assetProxyContracts,
         uint256 _required,
@@ -59,7 +67,10 @@ contract AssetProxyOwner is
     {
         for (uint256 i = 0; i < _assetProxyContracts.length; i++) {
             address assetProxy = _assetProxyContracts[i];
-            require(assetProxy != address(0));
+            require(
+                assetProxy != address(0),
+                "INVALID_ASSET_PROXY"
+            );
             isAssetProxyRegistered[assetProxy] = true;
         }
     }
@@ -74,7 +85,7 @@ contract AssetProxyOwner is
         notNull(assetProxyContract)
     {
         isAssetProxyRegistered[assetProxyContract] = isRegistered;
-        AssetProxyRegistration(assetProxyContract, isRegistered);
+        emit AssetProxyRegistration(assetProxyContract, isRegistered);
     }
 
     /// @dev Allows execution of `removeAuthorizedAddressAtIndex` without time lock.
@@ -85,35 +96,13 @@ contract AssetProxyOwner is
         fullyConfirmed(transactionId)
         validRemoveAuthorizedAddressAtIndexTx(transactionId)
     {
-        Transaction storage tx = transactions[transactionId];
-        tx.executed = true;
-        // solhint-disable-next-line avoid-call-value
-        if (tx.destination.call.value(tx.value)(tx.data))
-            Execution(transactionId);
-        else {
-            ExecutionFailure(transactionId);
-            tx.executed = false;
+        Transaction storage txn = transactions[transactionId];
+        txn.executed = true;
+        if (external_call(txn.destination, txn.value, txn.data.length, txn.data)) {
+            emit Execution(transactionId);
+        } else {
+            emit ExecutionFailure(transactionId);
+            txn.executed = false;
         }
     }
-
-    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
-    /// @param b Byte array containing a bytes4 value.
-    /// @param index Index in byte array of bytes4 value.
-    /// @return bytes4 value from byte array.
-    function readBytes4(
-        bytes memory b,
-        uint256 index
-    )
-        internal
-        returns (bytes4 result)
-    {
-        require(b.length >= index + 4);
-        assembly {
-            result := mload(add(b, 32))
-            // Solidity does not require us to clean the trailing bytes.
-            // We do it anyway
-            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
-        }
-        return result;
-    }
 }
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
index 7507d3da1..ead36009f 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
@@ -37,7 +37,6 @@ contract Exchange is
     MixinAssetProxyDispatcher,
     MixinWrapperFunctions
 {
-
     string constant public VERSION = "2.0.1-alpha";
 
     // Mixins are instantiated in the order they are inherited
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
index 80475e6e3..87b09b6b3 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -19,7 +19,6 @@
 pragma solidity 0.4.24;
 
 import "../../utils/Ownable/Ownable.sol";
-import "../../utils/LibBytes/LibBytes.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
 import "../AssetProxy/interfaces/IAssetProxy.sol";
 
@@ -28,8 +27,6 @@ contract MixinAssetProxyDispatcher is
     Ownable,
     MAssetProxyDispatcher
 {
-    using LibBytes for bytes;
-    
     // Mapping from Asset Proxy Id's to their respective Asset Proxy
     mapping (bytes4 => IAssetProxy) public assetProxies;
 
@@ -90,7 +87,7 @@ contract MixinAssetProxyDispatcher is
                 "LENGTH_GREATER_THAN_3_REQUIRED"
             );
             
-            // Lookup assetProxy
+            // Lookup assetProxy. We do not use `LibBytes.readBytes4` for gas efficiency reasons.
             bytes4 assetProxyId;
             assembly {
                 assetProxyId := and(mload(
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
index be163ec97..736dcd0b1 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -75,7 +75,11 @@ contract MixinExchangeCore is
 
         // Update orderEpoch
         orderEpoch[makerAddress][senderAddress] = newOrderEpoch;
-        emit CancelUpTo(makerAddress, senderAddress, newOrderEpoch);
+        emit CancelUpTo(
+            makerAddress,
+            senderAddress,
+            newOrderEpoch
+        );
     }
 
     /// @dev Fills the input order.
@@ -107,14 +111,7 @@ contract MixinExchangeCore is
         public
         nonReentrant
     {
-        // Fetch current order status
-        OrderInfo memory orderInfo = getOrderInfo(order);
-
-        // Validate context
-        assertValidCancel(order, orderInfo);
-
-        // Perform cancel
-        updateCancelledState(order, orderInfo.orderHash);
+        cancelOrderInternal(order);
     }
 
     /// @dev Gets information about an order: status, hash, and amount filled.
@@ -231,11 +228,31 @@ contract MixinExchangeCore is
         );
     
         // Settle order
-        settleOrder(order, takerAddress, fillResults);
+        settleOrder(
+            order,
+            takerAddress,
+            fillResults
+        );
 
         return fillResults;
     }
 
+    /// @dev After calling, the order can not be filled anymore.
+    ///      Throws if order is invalid or sender does not have permission to cancel.
+    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
+    function cancelOrderInternal(Order memory order)
+        internal
+    {
+        // Fetch current order status
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Validate context
+        assertValidCancel(order, orderInfo);
+
+        // Perform cancel
+        updateCancelledState(order, orderInfo.orderHash);
+    }
+
     /// @dev Updates state with results of a fill order.
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
@@ -404,16 +421,6 @@ contract MixinExchangeCore is
             safeMul(order.makerAssetAmount, takerAssetFilledAmount),
             "INVALID_FILL_PRICE"
         );
-        
-        // Validate fill order rounding
-        require(
-            !isRoundingErrorFloor(
-                takerAssetFilledAmount,
-                order.takerAssetAmount,
-                order.makerAssetAmount
-            ),
-            "ROUNDING_ERROR"
-        );
     }
 
     /// @dev Validates context for cancelOrder. Succeeds or throws.
@@ -463,17 +470,17 @@ contract MixinExchangeCore is
     {
         // Compute proportional transfer amounts
         fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
-        fillResults.makerAssetFilledAmount = getPartialAmountFloor(
+        fillResults.makerAssetFilledAmount = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerAssetAmount
         );
-        fillResults.makerFeePaid = getPartialAmountFloor(
-            takerAssetFilledAmount,
-            order.takerAssetAmount,
+        fillResults.makerFeePaid = safeGetPartialAmountFloor(
+            fillResults.makerAssetFilledAmount,
+            order.makerAssetAmount,
             order.makerFee
         );
-        fillResults.takerFeePaid = getPartialAmountFloor(
+        fillResults.takerFeePaid = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.takerFee
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
index 075a610b5..b4f6bdb26 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
@@ -177,13 +177,13 @@ contract MixinMatchOrders is
     {
         // Derive maker asset amounts for left & right orders, given store taker assert amounts
         uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderTakerAssetFilledAmount);
-        uint256 leftMakerAssetAmountRemaining = getPartialAmountFloor(
+        uint256 leftMakerAssetAmountRemaining = safeGetPartialAmountFloor(
             leftOrder.makerAssetAmount,
             leftOrder.takerAssetAmount,
             leftTakerAssetAmountRemaining
         );
         uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderTakerAssetFilledAmount);
-        uint256 rightMakerAssetAmountRemaining = getPartialAmountFloor(
+        uint256 rightMakerAssetAmountRemaining = safeGetPartialAmountFloor(
             rightOrder.makerAssetAmount,
             rightOrder.takerAssetAmount,
             rightTakerAssetAmountRemaining
@@ -205,7 +205,7 @@ contract MixinMatchOrders is
             matchedFillResults.left.takerAssetFilledAmount = matchedFillResults.right.makerAssetFilledAmount;
             // Round down to ensure the maker's exchange rate does not exceed the price specified by the order. 
             // We favor the maker when the exchange rate must be rounded.
-            matchedFillResults.left.makerAssetFilledAmount = getPartialAmountFloor(
+            matchedFillResults.left.makerAssetFilledAmount = safeGetPartialAmountFloor(
                 leftOrder.makerAssetAmount,
                 leftOrder.takerAssetAmount,
                 matchedFillResults.left.takerAssetFilledAmount
@@ -217,7 +217,7 @@ contract MixinMatchOrders is
             matchedFillResults.right.makerAssetFilledAmount = matchedFillResults.left.takerAssetFilledAmount;
             // Round up to ensure the maker's exchange rate does not exceed the price specified by the order.
             // We favor the maker when the exchange rate must be rounded.
-            matchedFillResults.right.takerAssetFilledAmount = getPartialAmountCeil(
+            matchedFillResults.right.takerAssetFilledAmount = safeGetPartialAmountCeil(
                 rightOrder.takerAssetAmount,
                 rightOrder.makerAssetAmount,
                 matchedFillResults.right.makerAssetFilledAmount
@@ -231,24 +231,24 @@ contract MixinMatchOrders is
         );
 
         // Compute fees for left order
-        matchedFillResults.left.makerFeePaid = getPartialAmountFloor(
+        matchedFillResults.left.makerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.left.makerAssetFilledAmount,
             leftOrder.makerAssetAmount,
             leftOrder.makerFee
         );
-        matchedFillResults.left.takerFeePaid = getPartialAmountFloor(
+        matchedFillResults.left.takerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.left.takerAssetFilledAmount,
             leftOrder.takerAssetAmount,
             leftOrder.takerFee
         );
 
         // Compute fees for right order
-        matchedFillResults.right.makerFeePaid = getPartialAmountFloor(
+        matchedFillResults.right.makerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.right.makerAssetFilledAmount,
             rightOrder.makerAssetAmount,
             rightOrder.makerFee
         );
-        matchedFillResults.right.takerFeePaid = getPartialAmountFloor(
+        matchedFillResults.right.takerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.right.takerAssetFilledAmount,
             rightOrder.takerAssetAmount,
             rightOrder.takerFee
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
index 4eb6a2fa6..176e28351 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
@@ -251,7 +251,7 @@ contract MixinSignatureValidator is
                 walletAddress,    // address of Wallet contract
                 cdStart,          // pointer to start of input
                 mload(calldata),  // length of input
-                cdStart,          // write input over output
+                cdStart,          // write output over input
                 32                // output size is 32 bytes
             )
 
@@ -301,7 +301,7 @@ contract MixinSignatureValidator is
                 validatorAddress,  // address of Validator contract
                 cdStart,           // pointer to start of input
                 mload(calldata),   // length of input
-                cdStart,           // write input over output
+                cdStart,           // write output over input
                 32                 // output size is 32 bytes
             )
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
index 4a59b6c0f..3a76ca202 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -28,7 +28,6 @@ contract MixinTransactions is
     MSignatureValidator,
     MTransactions
 {
-
     // Mapping of transaction hash => executed
     // This prevents transactions from being executed more than once.
     mapping (bytes32 => bool) public transactions;
@@ -36,15 +35,6 @@ contract MixinTransactions is
     // Address of current transaction signer
     address public currentContextAddress;
 
-    // Hash for the EIP712 ZeroEx Transaction Schema
-    bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
-        "ZeroExTransaction(",
-        "uint256 salt,",
-        "address signerAddress,",
-        "bytes data",
-        ")"
-    ));
-
     /// @dev Executes an exchange method call in the context of signer.
     /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
     /// @param signerAddress Address of transaction signer.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
index a5459a21e..cddff0e5f 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
@@ -36,7 +36,6 @@ contract MixinWrapperFunctions is
     MExchangeCore,
     MWrapperFunctions
 {
-
     /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
     /// @param order Order struct containing order specifications.
     /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
@@ -82,7 +81,7 @@ contract MixinWrapperFunctions is
         // Delegate to `fillOrder` and handle any exceptions gracefully
         assembly {
             let success := delegatecall(
-                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                gas,                                // forward all gas
                 address,                            // call address of this contract
                 add(fillOrderCalldata, 32),         // pointer to start of input (skip array length in first 32 bytes)
                 mload(fillOrderCalldata),           // length of input
@@ -377,10 +376,11 @@ contract MixinWrapperFunctions is
     /// @param orders Array of order specifications.
     function batchCancelOrders(LibOrder.Order[] memory orders)
         public
+        nonReentrant
     {
         uint256 ordersLength = orders.length;
         for (uint256 i = 0; i != ordersLength; i++) {
-            cancelOrder(orders[i]);
+            cancelOrderInternal(orders[i]);
         }
     }
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
index b02f7632e..203edc1fd 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
@@ -20,6 +20,7 @@ pragma solidity 0.4.24;
 
 
 contract LibEIP712 {
+
     // EIP191 header for EIP712 prefix
     string constant internal EIP191_HEADER = "\x19\x01";
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
index 1b4181d94..659ae9a69 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
@@ -24,7 +24,6 @@ import "../../../utils/SafeMath/SafeMath.sol";
 contract LibFillResults is
     SafeMath
 {
-
     struct FillResults {
         uint256 makerAssetFilledAmount;  // Total amount of makerAsset(s) filled.
         uint256 takerAssetFilledAmount;  // Total amount of takerAsset(s) filled.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
index 0e0fba5d2..c0b85ea10 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
@@ -24,6 +24,83 @@ import "../../../utils/SafeMath/SafeMath.sol";
 contract LibMath is
     SafeMath
 {
+    /// @dev Calculates partial value given a numerator and denominator rounded down.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target rounded down.
+    function safeGetPartialAmountFloor(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        require(
+            denominator > 0,
+            "DIVISION_BY_ZERO"
+        );
+
+        require(
+            !isRoundingErrorFloor(
+                numerator,
+                denominator,
+                target
+            ),
+            "ROUNDING_ERROR"
+        );
+        
+        partialAmount = safeDiv(
+            safeMul(numerator, target),
+            denominator
+        );
+        return partialAmount;
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator rounded down.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target rounded up.
+    function safeGetPartialAmountCeil(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        require(
+            denominator > 0,
+            "DIVISION_BY_ZERO"
+        );
+
+        require(
+            !isRoundingErrorCeil(
+                numerator,
+                denominator,
+                target
+            ),
+            "ROUNDING_ERROR"
+        );
+        
+        // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
+        //       ceil(a / b) = floor((a + b - 1) / b)
+        // To implement `ceil(a / b)` using safeDiv.
+        partialAmount = safeDiv(
+            safeAdd(
+                safeMul(numerator, target),
+                safeSub(denominator, 1)
+            ),
+            denominator
+        );
+        return partialAmount;
+    }
 
     /// @dev Calculates partial value given a numerator and denominator rounded down.
     /// @param numerator Numerator.
@@ -43,7 +120,7 @@ contract LibMath is
             denominator > 0,
             "DIVISION_BY_ZERO"
         );
-        
+
         partialAmount = safeDiv(
             safeMul(numerator, target),
             denominator
@@ -69,7 +146,7 @@ contract LibMath is
             denominator > 0,
             "DIVISION_BY_ZERO"
         );
-        
+
         // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
         //       ceil(a / b) = floor((a + b - 1) / b)
         // To implement `ceil(a / b)` using safeDiv.
@@ -128,7 +205,11 @@ contract LibMath is
         //        1000 * remainder  <  numerator * target
         // so we have a rounding error iff:
         //        1000 * remainder  >=  numerator * target
-        uint256 remainder = mulmod(target, numerator, denominator);
+        uint256 remainder = mulmod(
+            target,
+            numerator,
+            denominator
+        );
         isError = safeMul(1000, remainder) >= safeMul(numerator, target);
         return isError;
     }
@@ -160,8 +241,11 @@ contract LibMath is
             return false;
         }
         // Compute remainder as before
-        uint256 remainder = mulmod(target, numerator, denominator);
-        // TODO: safeMod
+        uint256 remainder = mulmod(
+            target,
+            numerator,
+            denominator
+        );
         remainder = safeSub(denominator, remainder) % denominator;
         isError = safeMul(1000, remainder) >= safeMul(numerator, target);
         return isError;
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
index 68f4f5f1b..0fe7c2161 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -24,7 +24,6 @@ import "./LibEIP712.sol";
 contract LibOrder is
     LibEIP712
 {
-
     // Hash for the EIP712 Order Schema
     bytes32 constant internal EIP712_ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
         "Order(",
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
index c6904300a..0ddfca270 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAssetProxyDispatcher.sol";
 contract MAssetProxyDispatcher is
     IAssetProxyDispatcher
 {
-
     // Logs registration of new asset proxy
     event AssetProxyRegistered(
         bytes4 id,              // Id of new registered AssetProxy.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
index d85913e0f..742499568 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
@@ -72,6 +72,11 @@ contract MExchangeCore is
         internal
         returns (LibFillResults.FillResults memory fillResults);
 
+    /// @dev After calling, the order can not be filled anymore.
+    /// @param order Order struct containing order specifications.
+    function cancelOrderInternal(LibOrder.Order memory order)
+        internal;
+
     /// @dev Updates state with results of a fill order.
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
index a31ec1585..96fa34bc0 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
@@ -26,7 +26,6 @@ import "../interfaces/IMatchOrders.sol";
 contract MMatchOrders is
     IMatchOrders
 {
-
     /// @dev Validates context for matchOrders. Succeeds or throws.
     /// @param leftOrder First order to match.
     /// @param rightOrder Second order to match.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
index f2b5e4b16..4f61a4945 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
@@ -23,6 +23,28 @@ import "../interfaces/ITransactions.sol";
 contract MTransactions is
     ITransactions
 {
+    // Hash for the EIP712 ZeroEx Transaction Schema
+    bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "ZeroExTransaction(",
+        "uint256 salt,",
+        "address signerAddress,",
+        "bytes data",
+        ")"
+    ));
+
+    /// @dev Calculates EIP712 hash of the Transaction.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @return EIP712 hash of the Transaction.
+    function hashZeroExTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes memory data
+    )
+        internal
+        pure
+        returns (bytes32 result);
 
     /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
     ///      If calling a fill function, this address will represent the taker.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
index e04d4a429..4adfbde01 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
@@ -24,8 +24,9 @@ import "../libs/LibFillResults.sol";
 import "../interfaces/IWrapperFunctions.sol";
 
 
-contract MWrapperFunctions {
-
+contract MWrapperFunctions is 
+    IWrapperFunctions
+{
     /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
     /// @param order LibOrder.Order struct containing order specifications.
     /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
diff --git a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol
new file mode 100644
index 000000000..733d4437e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol
@@ -0,0 +1,69 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "./DummyERC20Token.sol";
+
+
+// solhint-disable no-empty-blocks
+contract DummyMultipleReturnERC20Token is
+    DummyERC20Token
+{
+    constructor (
+        string _name,
+        string _symbol,
+        uint256 _decimals,
+        uint256 _totalSupply
+    )
+        public
+        DummyERC20Token(
+            _name,
+            _symbol,
+            _decimals,
+            _totalSupply
+        )
+    {}
+
+    /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
+    /// @param _from The address of the sender
+    /// @param _to The address of the recipient
+    /// @param _value The amount of token to be transferred
+    function transferFrom(
+        address _from,
+        address _to,
+        uint256 _value
+    )
+        external
+        returns (bool)
+    {
+        emit Transfer(
+            _from,
+            _to,
+            _value
+        );
+
+        // HACK: This contract will not compile if we remove `returns (bool)`, so we manually return 64 bytes (equiavalent to true, true)
+        assembly {
+            mstore(0, 1)
+            mstore(32, 1)
+            return(0, 64)
+        }
+    }
+}
+
diff --git a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
index 79156d3dd..e16825a16 100644
--- a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
@@ -25,7 +25,6 @@ import "./DummyERC20Token.sol";
 contract DummyNoReturnERC20Token is
     DummyERC20Token
 {
-
     constructor (
         string _name,
         string _symbol,
diff --git a/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
index ac95e47bd..6c8371559 100644
--- a/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
@@ -24,7 +24,6 @@ import "../../tokens/ERC721Token/IERC721Receiver.sol";
 contract DummyERC721Receiver is
     IERC721Receiver
 {
-
     // Function selector for ERC721Receiver.onERC721Received
     // 0x150b7a02
     bytes4 constant internal ERC721_RECEIVED = bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"));
diff --git a/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol b/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
index 8bfdd2e66..99dd47a78 100644
--- a/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
+++ b/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
@@ -25,10 +25,10 @@ import "../../protocol/Exchange/interfaces/IExchange.sol";
 import "../../protocol/Exchange/libs/LibOrder.sol";
 
 
+// solhint-disable no-unused-vars
 contract ReentrantERC20Token is
     ERC20Token
 {
-
     using LibBytes for bytes;
 
     // solhint-disable-next-line var-name-mixedcase
@@ -50,6 +50,7 @@ contract ReentrantERC20Token is
         MARKET_SELL_ORDERS,
         MATCH_ORDERS,
         CANCEL_ORDER,
+        BATCH_CANCEL_ORDERS,
         CANCEL_ORDERS_UP_TO,
         SET_SIGNATURE_VALIDATOR_APPROVAL
     }
@@ -149,6 +150,11 @@ contract ReentrantERC20Token is
                 EXCHANGE.cancelOrder.selector,
                 order
             );
+        } else if (currentFunctionId == uint8(ExchangeFunction.BATCH_CANCEL_ORDERS)) {
+            calldata = abi.encodeWithSelector(
+                EXCHANGE.batchCancelOrders.selector,
+                orders
+            );
         } else if (currentFunctionId == uint8(ExchangeFunction.CANCEL_ORDERS_UP_TO)) {
             calldata = abi.encodeWithSelector(
                 EXCHANGE.cancelOrdersUpTo.selector,
diff --git a/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
index 75e782d43..52c66cb56 100644
--- a/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
@@ -16,7 +16,7 @@
 
 */
 
-pragma solidity 0.4.10;
+pragma solidity 0.4.24;
 
 import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
 
@@ -25,8 +25,7 @@ import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
 contract TestAssetProxyOwner is
     AssetProxyOwner
 {
-
-    function TestAssetProxyOwner(
+    constructor (
         address[] memory _owners,
         address[] memory _assetProxyContracts,
         uint256 _required,
@@ -38,6 +37,7 @@ contract TestAssetProxyOwner is
     
     function testValidRemoveAuthorizedAddressAtIndexTx(uint256 id)
         public
+        view
         validRemoveAuthorizedAddressAtIndexTx(id)
         returns (bool)
     {
@@ -50,23 +50,9 @@ contract TestAssetProxyOwner is
     /// @return Successful if data is a call to `removeAuthorizedAddressAtIndex`.
     function isFunctionRemoveAuthorizedAddressAtIndex(bytes memory data)
         public
+        pure
         returns (bool)
     {
-        return readBytes4(data, 0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
-    }
-
-    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
-    /// @param b Byte array containing a bytes4 value.
-    /// @param index Index in byte array of bytes4 value.
-    /// @return bytes4 value from byte array.
-    function publicReadBytes4(
-        bytes memory b,
-        uint256 index
-    )
-        public
-        returns (bytes4 result)
-    {
-        result = readBytes4(b, index);
-        return result;
+        return data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
     }
 }
diff --git a/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
index da9313e02..27187f8f8 100644
--- a/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
+++ b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
@@ -63,6 +63,42 @@ contract TestExchangeInternals is
     }
 
     /// @dev Calculates partial value given a numerator and denominator.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function publicSafeGetPartialAmountFloor(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        return safeGetPartialAmountFloor(numerator, denominator, target);
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function publicSafeGetPartialAmountCeil(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        return safeGetPartialAmountCeil(numerator, denominator, target);
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator.
     /// @param numerator Numerator.
     /// @param denominator Denominator.
     /// @param target Value to calculate partial of.
diff --git a/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
index c8c58545f..a10f981fc 100644
--- a/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
+++ b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
@@ -31,7 +31,6 @@ contract TestLibs is
     LibFillResults,
     LibAbiEncoder
 {
-
     function publicAbiEncodeFillOrder(
         Order memory order,
         uint256 takerAssetFillAmount,
diff --git a/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
index e1a610469..ea3e2de59 100644
--- a/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
@@ -26,7 +26,6 @@ contract TestSignatureValidator is
     MixinSignatureValidator,
     MixinTransactions
 {
-
     function publicIsValidSignature(
         bytes32 hash,
         address signer,
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
index 5ef5ee7ce..725d304df 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
@@ -24,7 +24,6 @@ import "./IERC20Token.sol";
 contract ERC20Token is
     IERC20Token
 {
-
     mapping (address => uint256) internal balances;
     mapping (address => mapping (address => uint256)) internal allowed;
 
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
index cd1c7b4bb..9dc924422 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
@@ -26,7 +26,6 @@ contract MintableERC20Token is
     SafeMath,
     UnlimitedAllowanceERC20Token
 {
-
     /// @dev Mints new tokens
     /// @param _to Address of the beneficiary that will own the minted token
     /// @param _value Amount of tokens to mint
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
index e6f7c063e..2e5bd4348 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
@@ -24,7 +24,6 @@ import "../ERC20Token/ERC20Token.sol";
 contract UnlimitedAllowanceERC20Token is
     ERC20Token
 {
-
     uint256 constant internal MAX_UINT = 2**256 - 1;
 
     /// @dev ERC20 transferFrom, modified such that an allowance of MAX_UINT represents an unlimited allowance. See https://github.com/ethereum/EIPs/issues/717
diff --git a/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
index 85d192779..bc5cd2cc2 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
@@ -24,7 +24,6 @@ import "./ERC721Token.sol";
 contract MintableERC721Token is
     ERC721Token
 {
-
     /// @dev Function to mint a new token
     ///      Reverts if the given token ID already exists
     /// @param _to Address of the beneficiary that will own the minted token
diff --git a/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
index 28c0b2fb3..f4855759c 100644
--- a/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
+++ b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
@@ -22,11 +22,13 @@ pragma solidity 0.4.11;
 import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
 
 
-contract ZRXToken is UnlimitedAllowanceToken {
+contract ZRXToken is 
+    UnlimitedAllowanceToken
+{
 
     // solhint-disable const-name-snakecase
     uint8 constant public decimals = 18;
-    uint public totalSupply = 10**27; // 1 billion tokens, 18 decimal places
+    uint256 public totalSupply = 10**27; // 1 billion tokens, 18 decimal places
     string constant public name = "0x Protocol Token";
     string constant public symbol = "ZRX";
     // solhint-enableconst-name-snakecase
diff --git a/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
index 504e950a8..369f588ad 100644
--- a/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
@@ -188,7 +188,8 @@ library LibBytes {
         memCopy(
             result.contentAddress(),
             b.contentAddress() + from,
-            result.length);
+            result.length
+        );
         return result;
     }
     
@@ -433,7 +434,8 @@ library LibBytes {
         pure
         returns (uint256 result)
     {
-        return uint256(readBytes32(b, index));
+        result = uint256(readBytes32(b, index));
+        return result;
     }
 
     /// @dev Writes a uint256 into a specific position in a byte array.
@@ -467,8 +469,13 @@ library LibBytes {
             b.length >= index + 4,
             "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED"
         );
+
+        // Arrays are prefixed by a 32 byte length field
+        index += 32;
+
+        // Read the bytes4 from array memory
         assembly {
-            result := mload(add(b, 32))
+            result := mload(add(b, index))
             // Solidity does not require us to clean the trailing bytes.
             // We do it anyway
             result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
index 116b8dc89..5deb13497 100644
--- a/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
@@ -1,13 +1,8 @@
 pragma solidity 0.4.24;
 
-/*
- * Ownable
- *
- * Base contract with an owner.
- * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
- */
 
 contract IOwnable {
+
     function transferOwnership(address newOwner)
         public;
 }
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
index aca65aad2..0c830be68 100644
--- a/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
@@ -1,16 +1,11 @@
 pragma solidity 0.4.24;
 
-/*
- * Ownable
- *
- * Base contract with an owner.
- * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
- */
-
 import "./IOwnable.sol";
 
 
-contract Ownable is IOwnable {
+contract Ownable is
+    IOwnable
+{
     address public owner;
 
     constructor ()
diff --git a/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol b/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
index 1dee512d4..9f98a7a16 100644
--- a/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
+++ b/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
@@ -15,6 +15,7 @@
   limitations under the License.
 
 */
+
 pragma solidity 0.4.24;
 
 
diff --git a/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
index 63a2a085f..2855edb9d 100644
--- a/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
+++ b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
@@ -2,6 +2,7 @@ pragma solidity 0.4.24;
 
 
 contract SafeMath {
+
     function safeMul(uint256 a, uint256 b)
         internal
         pure
diff --git a/packages/contracts/test/asset_proxy/authorizable.ts b/packages/contracts/test/asset_proxy/authorizable.ts
index e99c6cee3..0c0da46b3 100644
--- a/packages/contracts/test/asset_proxy/authorizable.ts
+++ b/packages/contracts/test/asset_proxy/authorizable.ts
@@ -2,6 +2,7 @@ import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
+import * as _ from 'lodash';
 
 import { MixinAuthorizableContract } from '../../generated_contract_wrappers/mixin_authorizable';
 import { artifacts } from '../utils/artifacts';
@@ -28,8 +29,7 @@ describe('Authorizable', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        owner = address = accounts[0];
-        notOwner = accounts[1];
+        [owner, address, notOwner] = _.slice(accounts, 0, 3);
         authorizable = await MixinAuthorizableContract.deployFrom0xArtifactAsync(
             artifacts.MixinAuthorizable,
             provider,
diff --git a/packages/contracts/test/asset_proxy/proxies.ts b/packages/contracts/test/asset_proxy/proxies.ts
index 6031e554d..4d70031d1 100644
--- a/packages/contracts/test/asset_proxy/proxies.ts
+++ b/packages/contracts/test/asset_proxy/proxies.ts
@@ -8,6 +8,8 @@ import * as _ from 'lodash';
 import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_erc20_token';
 import { DummyERC721ReceiverContract } from '../../generated_contract_wrappers/dummy_erc721_receiver';
 import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_erc721_token';
+import { DummyMultipleReturnERC20TokenContract } from '../../generated_contract_wrappers/dummy_multiple_return_erc20_token';
+import { DummyNoReturnERC20TokenContract } from '../../generated_contract_wrappers/dummy_no_return_erc20_token';
 import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_proxy';
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { IAssetProxyContract } from '../../generated_contract_wrappers/i_asset_proxy';
@@ -42,6 +44,8 @@ describe('Asset Transfer Proxies', () => {
     let erc721Receiver: DummyERC721ReceiverContract;
     let erc20Proxy: ERC20ProxyContract;
     let erc721Proxy: ERC721ProxyContract;
+    let noReturnErc20Token: DummyNoReturnERC20TokenContract;
+    let multipleReturnErc20Token: DummyMultipleReturnERC20TokenContract;
 
     let erc20Wrapper: ERC20Wrapper;
     let erc721Wrapper: ERC721Wrapper;
@@ -91,6 +95,51 @@ describe('Asset Transfer Proxies', () => {
             provider,
             txDefaults,
         );
+        noReturnErc20Token = await DummyNoReturnERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.DummyNoReturnERC20Token,
+            provider,
+            txDefaults,
+            constants.DUMMY_TOKEN_NAME,
+            constants.DUMMY_TOKEN_SYMBOL,
+            constants.DUMMY_TOKEN_DECIMALS,
+            constants.DUMMY_TOKEN_TOTAL_SUPPLY,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await noReturnErc20Token.setBalance.sendTransactionAsync(makerAddress, constants.INITIAL_ERC20_BALANCE),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await noReturnErc20Token.approve.sendTransactionAsync(
+                erc20Proxy.address,
+                constants.INITIAL_ERC20_ALLOWANCE,
+                { from: makerAddress },
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        multipleReturnErc20Token = await DummyMultipleReturnERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.DummyMultipleReturnERC20Token,
+            provider,
+            txDefaults,
+            constants.DUMMY_TOKEN_NAME,
+            constants.DUMMY_TOKEN_SYMBOL,
+            constants.DUMMY_TOKEN_DECIMALS,
+            constants.DUMMY_TOKEN_TOTAL_SUPPLY,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await multipleReturnErc20Token.setBalance.sendTransactionAsync(
+                makerAddress,
+                constants.INITIAL_ERC20_BALANCE,
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+        await web3Wrapper.awaitTransactionSuccessAsync(
+            await multipleReturnErc20Token.approve.sendTransactionAsync(
+                erc20Proxy.address,
+                constants.INITIAL_ERC20_ALLOWANCE,
+                { from: makerAddress },
+            ),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
     });
     beforeEach(async () => {
         await blockchainLifecycle.startAsync();
@@ -141,6 +190,65 @@ describe('Asset Transfer Proxies', () => {
                 );
             });
 
+            it('should successfully transfer tokens that do not return a value', async () => {
+                // Construct ERC20 asset data
+                const encodedAssetData = assetDataUtils.encodeERC20AssetData(noReturnErc20Token.address);
+                // Perform a transfer from makerAddress to takerAddress
+                const initialMakerBalance = await noReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const initialTakerBalance = await noReturnErc20Token.balanceOf.callAsync(takerAddress);
+                const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
+                await web3Wrapper.awaitTransactionSuccessAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
+                    constants.AWAIT_TRANSACTION_MINED_MS,
+                );
+                // Verify transfer was successful
+                const newMakerBalance = await noReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const newTakerBalance = await noReturnErc20Token.balanceOf.callAsync(takerAddress);
+                expect(newMakerBalance).to.be.bignumber.equal(initialMakerBalance.minus(amount));
+                expect(newTakerBalance).to.be.bignumber.equal(initialTakerBalance.plus(amount));
+            });
+
+            it('should successfully transfer tokens and ignore extra assetData', async () => {
+                // Construct ERC20 asset data
+                const extraData = '0102030405060708';
+                const encodedAssetData = `${assetDataUtils.encodeERC20AssetData(zrxToken.address)}${extraData}`;
+                // Perform a transfer from makerAddress to takerAddress
+                const erc20Balances = await erc20Wrapper.getBalancesAsync();
+                const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
+                await web3Wrapper.awaitTransactionSuccessAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
+                    constants.AWAIT_TRANSACTION_MINED_MS,
+                );
+                // Verify transfer was successful
+                const newBalances = await erc20Wrapper.getBalancesAsync();
+                expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
+                    erc20Balances[makerAddress][zrxToken.address].minus(amount),
+                );
+                expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
+                    erc20Balances[takerAddress][zrxToken.address].add(amount),
+                );
+            });
+
             it('should do nothing if transferring 0 amount of a token', async () => {
                 // Construct ERC20 asset data
                 const encodedAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
@@ -189,6 +297,7 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     constants.AWAIT_TRANSACTION_MINED_MS,
                 );
+                const erc20Balances = await erc20Wrapper.getBalancesAsync();
                 // Perform a transfer; expect this to fail.
                 await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
@@ -198,6 +307,43 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.TransferFailed,
                 );
+                const newBalances = await erc20Wrapper.getBalancesAsync();
+                expect(newBalances).to.deep.equal(erc20Balances);
+            });
+
+            it('should throw if allowances are too low and token does not return a value', async () => {
+                // Construct ERC20 asset data
+                const encodedAssetData = assetDataUtils.encodeERC20AssetData(noReturnErc20Token.address);
+                // Create allowance less than transfer amount. Set allowance on proxy.
+                const allowance = new BigNumber(0);
+                const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
+                await web3Wrapper.awaitTransactionSuccessAsync(
+                    await noReturnErc20Token.approve.sendTransactionAsync(erc20Proxy.address, allowance, {
+                        from: makerAddress,
+                    }),
+                    constants.AWAIT_TRANSACTION_MINED_MS,
+                );
+                const initialMakerBalance = await noReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const initialTakerBalance = await noReturnErc20Token.balanceOf.callAsync(takerAddress);
+                // Perform a transfer; expect this to fail.
+                await expectTransactionFailedAsync(
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
+                    RevertReason.TransferFailed,
+                );
+                const newMakerBalance = await noReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const newTakerBalance = await noReturnErc20Token.balanceOf.callAsync(takerAddress);
+                expect(newMakerBalance).to.be.bignumber.equal(initialMakerBalance);
+                expect(newTakerBalance).to.be.bignumber.equal(initialTakerBalance);
             });
 
             it('should throw if requesting address is not authorized', async () => {
@@ -211,6 +357,7 @@ describe('Asset Transfer Proxies', () => {
                     takerAddress,
                     amount,
                 );
+                const erc20Balances = await erc20Wrapper.getBalancesAsync();
                 await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
                         to: erc20Proxy.address,
@@ -219,6 +366,35 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.SenderNotAuthorized,
                 );
+                const newBalances = await erc20Wrapper.getBalancesAsync();
+                expect(newBalances).to.deep.equal(erc20Balances);
+            });
+
+            it('should throw if token returns more than 32 bytes', async () => {
+                // Construct ERC20 asset data
+                const encodedAssetData = assetDataUtils.encodeERC20AssetData(multipleReturnErc20Token.address);
+                const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
+                const initialMakerBalance = await multipleReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const initialTakerBalance = await multipleReturnErc20Token.balanceOf.callAsync(takerAddress);
+                // Perform a transfer; expect this to fail.
+                await expectTransactionFailedAsync(
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
+                    RevertReason.TransferFailed,
+                );
+                const newMakerBalance = await multipleReturnErc20Token.balanceOf.callAsync(makerAddress);
+                const newTakerBalance = await multipleReturnErc20Token.balanceOf.callAsync(takerAddress);
+                expect(newMakerBalance).to.be.bignumber.equal(initialMakerBalance);
+                expect(newTakerBalance).to.be.bignumber.equal(initialTakerBalance);
             });
         });
 
@@ -247,7 +423,38 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Verify pre-condition
                 const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
-                expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
+                // Perform a transfer from makerAddress to takerAddress
+                const amount = new BigNumber(1);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
+                await web3Wrapper.awaitTransactionSuccessAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
+                    constants.AWAIT_TRANSACTION_MINED_MS,
+                );
+                // Verify transfer was successful
+                const newOwnerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(newOwnerMakerAsset).to.be.bignumber.equal(takerAddress);
+            });
+
+            it('should successfully transfer tokens and ignore extra assetData', async () => {
+                // Construct ERC721 asset data
+                const extraData = '0102030405060708';
+                const encodedAssetData = `${assetDataUtils.encodeERC721AssetData(
+                    erc721Token.address,
+                    erc721MakerTokenId,
+                )}${extraData}`;
+                // Verify pre-condition
+                const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
                 const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
@@ -274,7 +481,7 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Verify pre-condition
                 const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
-                expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
                 const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
@@ -304,7 +511,7 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Verify pre-condition
                 const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
-                expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(0);
                 const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
@@ -313,7 +520,7 @@ describe('Asset Transfer Proxies', () => {
                     takerAddress,
                     amount,
                 );
-                return expectTransactionFailedAsync(
+                await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
                         to: erc721Proxy.address,
                         data,
@@ -321,6 +528,8 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.InvalidAmount,
                 );
+                const newOwner = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(newOwner).to.be.equal(ownerMakerAsset);
             });
 
             it('should throw if transferring > 1 amount of a token', async () => {
@@ -328,7 +537,7 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Verify pre-condition
                 const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
-                expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(500);
                 const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
@@ -337,7 +546,7 @@ describe('Asset Transfer Proxies', () => {
                     takerAddress,
                     amount,
                 );
-                return expectTransactionFailedAsync(
+                await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
                         to: erc721Proxy.address,
                         data,
@@ -345,11 +554,16 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.InvalidAmount,
                 );
+                const newOwner = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(newOwner).to.be.equal(ownerMakerAsset);
             });
 
             it('should throw if allowances are too low', async () => {
                 // Construct ERC721 asset data
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
+                // Verify pre-condition
+                const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Remove transfer approval for makerAddress.
                 await web3Wrapper.awaitTransactionSuccessAsync(
                     await erc721Token.approve.sendTransactionAsync(constants.NULL_ADDRESS, erc721MakerTokenId, {
@@ -365,7 +579,7 @@ describe('Asset Transfer Proxies', () => {
                     takerAddress,
                     amount,
                 );
-                return expectTransactionFailedAsync(
+                await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
                         to: erc721Proxy.address,
                         data,
@@ -373,11 +587,16 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.TransferFailed,
                 );
+                const newOwner = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(newOwner).to.be.equal(ownerMakerAsset);
             });
 
             it('should throw if requesting address is not authorized', async () => {
                 // Construct ERC721 asset data
                 const encodedAssetData = assetDataUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
+                // Verify pre-condition
+                const ownerMakerAsset = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(ownerMakerAsset).to.be.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
                 const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
@@ -386,7 +605,7 @@ describe('Asset Transfer Proxies', () => {
                     takerAddress,
                     amount,
                 );
-                return expectTransactionFailedAsync(
+                await expectTransactionFailedAsync(
                     web3Wrapper.sendTransactionAsync({
                         to: erc721Proxy.address,
                         data,
@@ -394,6 +613,8 @@ describe('Asset Transfer Proxies', () => {
                     }),
                     RevertReason.SenderNotAuthorized,
                 );
+                const newOwner = await erc721Token.ownerOf.callAsync(erc721MakerTokenId);
+                expect(newOwner).to.be.equal(ownerMakerAsset);
             });
         });
 
diff --git a/packages/contracts/test/exchange/core.ts b/packages/contracts/test/exchange/core.ts
index 3bb71b58f..acb99eed1 100644
--- a/packages/contracts/test/exchange/core.ts
+++ b/packages/contracts/test/exchange/core.ts
@@ -8,7 +8,10 @@ import { LogWithDecodedArgs } from 'ethereum-types';
 import ethUtil = require('ethereumjs-util');
 import * as _ from 'lodash';
 
-import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_erc20_token';
+import {
+    DummyERC20TokenContract,
+    DummyERC20TokenTransferEventArgs,
+} from '../../generated_contract_wrappers/dummy_erc20_token';
 import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_erc721_token';
 import { DummyNoReturnERC20TokenContract } from '../../generated_contract_wrappers/dummy_no_return_erc20_token';
 import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_proxy';
@@ -243,6 +246,40 @@ describe('Exchange core', () => {
                 RevertReason.ValidatorError,
             );
         });
+
+        it('should not emit transfer events for transfers where from == to', async () => {
+            const txReceipt = await exchangeWrapper.fillOrderAsync(signedOrder, makerAddress);
+            const logs = txReceipt.logs;
+            const transferLogs = _.filter(
+                logs,
+                log => (log as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).event === 'Transfer',
+            );
+            expect(transferLogs.length).to.be.equal(2);
+            expect((transferLogs[0] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).address).to.be.equal(
+                zrxToken.address,
+            );
+            expect((transferLogs[0] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._from).to.be.equal(
+                makerAddress,
+            );
+            expect((transferLogs[0] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._to).to.be.equal(
+                feeRecipientAddress,
+            );
+            expect(
+                (transferLogs[0] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._value,
+            ).to.be.bignumber.equal(signedOrder.makerFee);
+            expect((transferLogs[1] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).address).to.be.equal(
+                zrxToken.address,
+            );
+            expect((transferLogs[1] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._from).to.be.equal(
+                makerAddress,
+            );
+            expect((transferLogs[1] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._to).to.be.equal(
+                feeRecipientAddress,
+            );
+            expect(
+                (transferLogs[1] as LogWithDecodedArgs<DummyERC20TokenTransferEventArgs>).args._value,
+            ).to.be.bignumber.equal(signedOrder.takerFee);
+        });
     });
 
     describe('Testing exchange of ERC20 tokens with no return values', () => {
diff --git a/packages/contracts/test/exchange/dispatcher.ts b/packages/contracts/test/exchange/dispatcher.ts
index 81871a680..a8ae897a8 100644
--- a/packages/contracts/test/exchange/dispatcher.ts
+++ b/packages/contracts/test/exchange/dispatcher.ts
@@ -205,6 +205,60 @@ describe('AssetProxyDispatcher', () => {
             );
         });
 
+        it('should not dispatch a transfer if amount == 0', async () => {
+            // Register ERC20 proxy
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            // Construct metadata for ERC20 proxy
+            const encodedAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
+
+            // Perform a transfer from makerAddress to takerAddress
+            const erc20Balances = await erc20Wrapper.getBalancesAsync();
+            const amount = constants.ZERO_AMOUNT;
+            const txReceipt = await web3Wrapper.awaitTransactionSuccessAsync(
+                await assetProxyDispatcher.publicDispatchTransferFrom.sendTransactionAsync(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                    { from: owner },
+                ),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            expect(txReceipt.logs.length).to.be.equal(0);
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            expect(newBalances).to.deep.equal(erc20Balances);
+        });
+
+        it('should not dispatch a transfer if from == to', async () => {
+            // Register ERC20 proxy
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            // Construct metadata for ERC20 proxy
+            const encodedAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
+
+            // Perform a transfer from makerAddress to takerAddress
+            const erc20Balances = await erc20Wrapper.getBalancesAsync();
+            const amount = new BigNumber(10);
+            const txReceipt = await web3Wrapper.awaitTransactionSuccessAsync(
+                await assetProxyDispatcher.publicDispatchTransferFrom.sendTransactionAsync(
+                    encodedAssetData,
+                    makerAddress,
+                    makerAddress,
+                    amount,
+                    { from: owner },
+                ),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            expect(txReceipt.logs.length).to.be.equal(0);
+            const newBalances = await erc20Wrapper.getBalancesAsync();
+            expect(newBalances).to.deep.equal(erc20Balances);
+        });
+
         it('should throw if dispatching to unregistered proxy', async () => {
             // Construct metadata for ERC20 proxy
             const encodedAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
diff --git a/packages/contracts/test/exchange/internal.ts b/packages/contracts/test/exchange/internal.ts
index de381fca3..156e086af 100644
--- a/packages/contracts/test/exchange/internal.ts
+++ b/packages/contracts/test/exchange/internal.ts
@@ -6,10 +6,7 @@ import * as _ from 'lodash';
 
 import { TestExchangeInternalsContract } from '../../generated_contract_wrappers/test_exchange_internals';
 import { artifacts } from '../utils/artifacts';
-import {
-    getInvalidOpcodeErrorMessageForCallAsync,
-    getRevertReasonOrErrorMessageForSendTransactionAsync,
-} from '../utils/assertions';
+import { getRevertReasonOrErrorMessageForSendTransactionAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { bytes32Values, testCombinatoriallyWithReferenceFuncAsync, uint256Values } from '../utils/combinatorial_utils';
 import { constants } from '../utils/constants';
@@ -48,9 +45,9 @@ const overflowErrorForCall = new Error(RevertReason.Uint256Overflow);
 
 describe('Exchange core internal functions', () => {
     let testExchange: TestExchangeInternalsContract;
-    let invalidOpcodeErrorForCall: Error | undefined;
     let overflowErrorForSendTransaction: Error | undefined;
     let divisionByZeroErrorForCall: Error | undefined;
+    let roundingErrorForCall: Error | undefined;
 
     before(async () => {
         await blockchainLifecycle.startAsync();
@@ -68,12 +65,67 @@ describe('Exchange core internal functions', () => {
             await getRevertReasonOrErrorMessageForSendTransactionAsync(RevertReason.Uint256Overflow),
         );
         divisionByZeroErrorForCall = new Error(RevertReason.DivisionByZero);
-        invalidOpcodeErrorForCall = new Error(await getInvalidOpcodeErrorMessageForCallAsync());
+        roundingErrorForCall = new Error(RevertReason.RoundingError);
     });
     // Note(albrow): Don't forget to add beforeEach and afterEach calls to reset
     // the blockchain state for any tests which modify it!
 
-    async function referenceGetPartialAmountFloorAsync(
+    async function referenceIsRoundingErrorFloorAsync(
+        numerator: BigNumber,
+        denominator: BigNumber,
+        target: BigNumber,
+    ): Promise<boolean> {
+        if (denominator.eq(0)) {
+            throw divisionByZeroErrorForCall;
+        }
+        if (numerator.eq(0)) {
+            return false;
+        }
+        if (target.eq(0)) {
+            return false;
+        }
+        const product = numerator.mul(target);
+        const remainder = product.mod(denominator);
+        const remainderTimes1000 = remainder.mul('1000');
+        const isError = remainderTimes1000.gte(product);
+        if (product.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        if (remainderTimes1000.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        return isError;
+    }
+
+    async function referenceIsRoundingErrorCeilAsync(
+        numerator: BigNumber,
+        denominator: BigNumber,
+        target: BigNumber,
+    ): Promise<boolean> {
+        if (denominator.eq(0)) {
+            throw divisionByZeroErrorForCall;
+        }
+        if (numerator.eq(0)) {
+            return false;
+        }
+        if (target.eq(0)) {
+            return false;
+        }
+        const product = numerator.mul(target);
+        const remainder = product.mod(denominator);
+        const error = denominator.sub(remainder).mod(denominator);
+        const errorTimes1000 = error.mul('1000');
+        const isError = errorTimes1000.gte(product);
+        if (product.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        if (errorTimes1000.greaterThan(MAX_UINT256)) {
+            throw overflowErrorForCall;
+        }
+        return isError;
+    }
+
+    async function referenceSafeGetPartialAmountFloorAsync(
         numerator: BigNumber,
         denominator: BigNumber,
         target: BigNumber,
@@ -81,6 +133,10 @@ describe('Exchange core internal functions', () => {
         if (denominator.eq(0)) {
             throw divisionByZeroErrorForCall;
         }
+        const isRoundingError = await referenceIsRoundingErrorFloorAsync(numerator, denominator, target);
+        if (isRoundingError) {
+            throw roundingErrorForCall;
+        }
         const product = numerator.mul(target);
         if (product.greaterThan(MAX_UINT256)) {
             throw overflowErrorForCall;
@@ -162,19 +218,22 @@ describe('Exchange core internal functions', () => {
             // in any mathematical operation in either the reference TypeScript
             // implementation or the Solidity implementation of
             // calculateFillResults.
+            const makerAssetFilledAmount = await referenceSafeGetPartialAmountFloorAsync(
+                takerAssetFilledAmount,
+                orderTakerAssetAmount,
+                otherAmount,
+            );
+            const order = makeOrder(otherAmount, orderTakerAssetAmount, otherAmount, otherAmount);
+            const orderMakerAssetAmount = order.makerAssetAmount;
             return {
-                makerAssetFilledAmount: await referenceGetPartialAmountFloorAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
-                    otherAmount,
-                ),
+                makerAssetFilledAmount,
                 takerAssetFilledAmount,
-                makerFeePaid: await referenceGetPartialAmountFloorAsync(
-                    takerAssetFilledAmount,
-                    orderTakerAssetAmount,
+                makerFeePaid: await referenceSafeGetPartialAmountFloorAsync(
+                    makerAssetFilledAmount,
+                    orderMakerAssetAmount,
                     otherAmount,
                 ),
-                takerFeePaid: await referenceGetPartialAmountFloorAsync(
+                takerFeePaid: await referenceSafeGetPartialAmountFloorAsync(
                     takerAssetFilledAmount,
                     orderTakerAssetAmount,
                     otherAmount,
@@ -198,6 +257,20 @@ describe('Exchange core internal functions', () => {
     });
 
     describe('getPartialAmountFloor', async () => {
+        async function referenceGetPartialAmountFloorAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
+            if (denominator.eq(0)) {
+                throw divisionByZeroErrorForCall;
+            }
+            const product = numerator.mul(target);
+            if (product.greaterThan(MAX_UINT256)) {
+                throw overflowErrorForCall;
+            }
+            return product.dividedToIntegerBy(denominator);
+        }
         async function testGetPartialAmountFloorAsync(
             numerator: BigNumber,
             denominator: BigNumber,
@@ -206,7 +279,7 @@ describe('Exchange core internal functions', () => {
             return testExchange.publicGetPartialAmountFloor.callAsync(numerator, denominator, target);
         }
         await testCombinatoriallyWithReferenceFuncAsync(
-            'getPartialAmount',
+            'getPartialAmountFloor',
             referenceGetPartialAmountFloorAsync,
             testGetPartialAmountFloorAsync,
             [uint256Values, uint256Values, uint256Values],
@@ -250,76 +323,80 @@ describe('Exchange core internal functions', () => {
         );
     });
 
-    describe('isRoundingError', async () => {
-        async function referenceIsRoundingErrorAsync(
+    describe('safeGetPartialAmountFloor', async () => {
+        async function testSafeGetPartialAmountFloorAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
-        ): Promise<boolean> {
+        ): Promise<BigNumber> {
+            return testExchange.publicSafeGetPartialAmountFloor.callAsync(numerator, denominator, target);
+        }
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'safeGetPartialAmountFloor',
+            referenceSafeGetPartialAmountFloorAsync,
+            testSafeGetPartialAmountFloorAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('safeGetPartialAmountCeil', async () => {
+        async function referenceSafeGetPartialAmountCeilAsync(
+            numerator: BigNumber,
+            denominator: BigNumber,
+            target: BigNumber,
+        ): Promise<BigNumber> {
             if (denominator.eq(0)) {
                 throw divisionByZeroErrorForCall;
             }
-            if (numerator.eq(0)) {
-                return false;
-            }
-            if (target.eq(0)) {
-                return false;
+            const isRoundingError = await referenceIsRoundingErrorCeilAsync(numerator, denominator, target);
+            if (isRoundingError) {
+                throw roundingErrorForCall;
             }
             const product = numerator.mul(target);
-            const remainder = product.mod(denominator);
-            const remainderTimes1000 = remainder.mul('1000');
-            const isError = remainderTimes1000.gt(product);
-            if (product.greaterThan(MAX_UINT256)) {
+            const offset = product.add(denominator.sub(1));
+            if (offset.greaterThan(MAX_UINT256)) {
                 throw overflowErrorForCall;
             }
-            if (remainderTimes1000.greaterThan(MAX_UINT256)) {
-                throw overflowErrorForCall;
+            const result = offset.dividedToIntegerBy(denominator);
+            if (product.mod(denominator).eq(0)) {
+                expect(result.mul(denominator)).to.be.bignumber.eq(product);
+            } else {
+                expect(result.mul(denominator)).to.be.bignumber.gt(product);
             }
-            return isError;
+            return result;
         }
-        async function testIsRoundingErrorAsync(
+        async function testSafeGetPartialAmountCeilAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
-        ): Promise<boolean> {
-            return testExchange.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
+        ): Promise<BigNumber> {
+            return testExchange.publicSafeGetPartialAmountCeil.callAsync(numerator, denominator, target);
         }
         await testCombinatoriallyWithReferenceFuncAsync(
-            'isRoundingError',
-            referenceIsRoundingErrorAsync,
-            testIsRoundingErrorAsync,
+            'safeGetPartialAmountCeil',
+            referenceSafeGetPartialAmountCeilAsync,
+            testSafeGetPartialAmountCeilAsync,
             [uint256Values, uint256Values, uint256Values],
         );
     });
 
-    describe('isRoundingErrorCeil', async () => {
-        async function referenceIsRoundingErrorAsync(
+    describe('isRoundingErrorFloor', async () => {
+        async function testIsRoundingErrorFloorAsync(
             numerator: BigNumber,
             denominator: BigNumber,
             target: BigNumber,
         ): Promise<boolean> {
-            if (denominator.eq(0)) {
-                throw divisionByZeroErrorForCall;
-            }
-            if (numerator.eq(0)) {
-                return false;
-            }
-            if (target.eq(0)) {
-                return false;
-            }
-            const product = numerator.mul(target);
-            const remainder = product.mod(denominator);
-            const error = denominator.sub(remainder).mod(denominator);
-            const errorTimes1000 = error.mul('1000');
-            const isError = errorTimes1000.gt(product);
-            if (product.greaterThan(MAX_UINT256)) {
-                throw overflowErrorForCall;
-            }
-            if (errorTimes1000.greaterThan(MAX_UINT256)) {
-                throw overflowErrorForCall;
-            }
-            return isError;
+            return testExchange.publicIsRoundingErrorFloor.callAsync(numerator, denominator, target);
         }
+        await testCombinatoriallyWithReferenceFuncAsync(
+            'isRoundingErrorFloor',
+            referenceIsRoundingErrorFloorAsync,
+            testIsRoundingErrorFloorAsync,
+            [uint256Values, uint256Values, uint256Values],
+        );
+    });
+
+    describe('isRoundingErrorCeil', async () => {
         async function testIsRoundingErrorCeilAsync(
             numerator: BigNumber,
             denominator: BigNumber,
@@ -329,7 +406,7 @@ describe('Exchange core internal functions', () => {
         }
         await testCombinatoriallyWithReferenceFuncAsync(
             'isRoundingErrorCeil',
-            referenceIsRoundingErrorAsync,
+            referenceIsRoundingErrorCeilAsync,
             testIsRoundingErrorCeilAsync,
             [uint256Values, uint256Values, uint256Values],
         );
diff --git a/packages/contracts/test/exchange/match_orders.ts b/packages/contracts/test/exchange/match_orders.ts
index 8732e20ba..c6e7b494f 100644
--- a/packages/contracts/test/exchange/match_orders.ts
+++ b/packages/contracts/test/exchange/match_orders.ts
@@ -3,6 +3,7 @@ import { assetDataUtils } from '@0xproject/order-utils';
 import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as chai from 'chai';
 import * as _ from 'lodash';
 
 import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_erc20_token';
@@ -11,8 +12,10 @@ import { ERC20ProxyContract } from '../../generated_contract_wrappers/erc20_prox
 import { ERC721ProxyContract } from '../../generated_contract_wrappers/erc721_proxy';
 import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
 import { ReentrantERC20TokenContract } from '../../generated_contract_wrappers/reentrant_erc20_token';
+import { TestExchangeInternalsContract } from '../../generated_contract_wrappers/test_exchange_internals';
 import { artifacts } from '../utils/artifacts';
 import { expectTransactionFailedAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { ERC20Wrapper } from '../utils/erc20_wrapper';
 import { ERC721Wrapper } from '../utils/erc721_wrapper';
@@ -23,6 +26,8 @@ import { ERC20BalancesByOwner, ERC721TokenIdsByOwner } from '../utils/types';
 import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+chaiSetup.configure();
+const expect = chai.expect;
 
 describe('matchOrders', () => {
     let makerAddressLeft: string;
@@ -58,6 +63,8 @@ describe('matchOrders', () => {
 
     let matchOrderTester: MatchOrderTester;
 
+    let testExchange: TestExchangeInternalsContract;
+
     before(async () => {
         await blockchainLifecycle.startAsync();
     });
@@ -160,6 +167,11 @@ describe('matchOrders', () => {
         orderFactoryRight = new OrderFactory(privateKeyRight, defaultOrderParamsRight);
         // Set match order tester
         matchOrderTester = new MatchOrderTester(exchangeWrapper, erc20Wrapper, erc721Wrapper, zrxToken.address);
+        testExchange = await TestExchangeInternalsContract.deployFrom0xArtifactAsync(
+            artifacts.TestExchangeInternals,
+            provider,
+            txDefaults,
+        );
     });
     beforeEach(async () => {
         await blockchainLifecycle.startAsync();
@@ -173,39 +185,170 @@ describe('matchOrders', () => {
             erc721TokenIdsByOwner = await erc721Wrapper.getBalancesAsync();
         });
 
-        it('Should give right maker a better price when correct price is not integral', async () => {
+        it('Should transfer correct amounts when right order is fully filled and values pass isRoundingErrorFloor but fail isRoundingErrorCeil', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAddress: makerAddressLeft,
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(17), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(98), 0),
+                feeRecipientAddress: feeRecipientAddressLeft,
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAddress: makerAddressRight,
+                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feeRecipientAddress: feeRecipientAddressRight,
+            });
+            // Assert is rounding error ceil & not rounding error floor
+            // These assertions are taken from MixinMatchOrders::calculateMatchedFillResults
+            // The rounding error is derived computating how much the left maker will sell.
+            const numerator = signedOrderLeft.makerAssetAmount;
+            const denominator = signedOrderLeft.takerAssetAmount;
+            const target = signedOrderRight.makerAssetAmount;
+            const isRoundingErrorCeil = await testExchange.publicIsRoundingErrorCeil.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorCeil).to.be.true();
+            const isRoundingErrorFloor = await testExchange.publicIsRoundingErrorFloor.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorFloor).to.be.false();
+            // Match signedOrderLeft with signedOrderRight
+            // Note that the left maker received a slightly better sell price.
+            // This is intentional; see note in MixinMatchOrders.calculateMatchedFillResults.
+            // Because the left maker received a slightly more favorable sell price, the fee
+            // paid by the left taker is slightly higher than that paid by the left maker.
+            // Fees can be thought of as a tax paid by the seller, derived from the sale price.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.4705882352941176'), 16), // 76.47%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(0), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber('76.5306122448979591'), 16), // 76.53%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('Should transfer correct amounts when left order is fully filled and values pass isRoundingErrorCeil but fail isRoundingErrorFloor', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2000), 0),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1001), 0),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(15), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10000), 0),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(3000), 0),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(97), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(14), 0),
+                feeRecipientAddress: feeRecipientAddressRight,
+            });
+            // Assert is rounding error floor & not rounding error ceil
+            // These assertions are taken from MixinMatchOrders::calculateMatchedFillResults
+            // The rounding error is derived computating how much the right maker will buy.
+            const numerator = signedOrderRight.takerAssetAmount;
+            const denominator = signedOrderRight.makerAssetAmount;
+            const target = signedOrderLeft.takerAssetAmount;
+            const isRoundingErrorFloor = await testExchange.publicIsRoundingErrorFloor.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorFloor).to.be.true();
+            const isRoundingErrorCeil = await testExchange.publicIsRoundingErrorCeil.callAsync(
+                numerator,
+                denominator,
+                target,
+            );
+            expect(isRoundingErrorCeil).to.be.false();
+            // Match signedOrderLeft with signedOrderRight
+            // Note that the right maker received a slightly better purchase price.
+            // This is intentional; see note in MixinMatchOrders.calculateMatchedFillResults.
+            // Because the right maker received a slightly more favorable buy price, the fee
+            // paid by the right taker is slightly higher than that paid by the right maker.
+            // Fees can be thought of as a tax paid by the seller, derived from the sale price.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(15), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(90), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('92.7835051546391752'), 16), // 92.78%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('92.8571428571428571'), 16), // 92.85%
+            };
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('Should give right maker a better buy price when rounding', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAddress: makerAddressLeft,
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
+                feeRecipientAddress: feeRecipientAddressLeft,
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAddress: makerAddressRight,
+                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(83), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(49), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
             });
             // Note:
+            // The correct price buy price for the right maker would yield (49/83) * 22 = 12.988 units
+            // of the left maker asset. This gets rounded up to 13, giving the right maker a better price.
+            // Note:
             //  The maker/taker fee percentage paid on the right order differs because
-            //  they received different sale prices. Similarly, the right maker pays a
-            //  slightly higher lower than the right taker.
+            //  they received different sale prices. The right maker pays a
+            //  fee slightly lower than the right taker.
             const expectedTransferAmounts = {
                 // Left Maker
-                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2000), 0),
-                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1001), 0),
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
                 feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
                 // Right Maker
-                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1001), 0),
-                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(301), 0),
-                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10.01), 16), // 10.01%
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('26.5060240963855421'), 16), // 26.506%
                 // Taker
-                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1699), 0),
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
                 feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
-                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('10.0333333333333333'), 16), // 10.03%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('26.5306122448979591'), 16), // 26.531%
             };
             // Match signedOrderLeft with signedOrderRight
             await matchOrderTester.matchOrdersAndAssertEffectsAsync(
@@ -218,7 +361,7 @@ describe('matchOrders', () => {
             );
         });
 
-        it('Should give left maker a better price when correct price is not integral', async () => {
+        it('Should give left maker a better sell price when rounding', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
@@ -236,7 +379,8 @@ describe('matchOrders', () => {
             });
             // Note:
             //  The maker/taker fee percentage paid on the left order differs because
-            //  they received different sale prices.
+            //  they received different sale prices. The left maker pays a fee
+            //  slightly lower than the left taker.
             const expectedTransferAmounts = {
                 // Left Maker
                 amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(11), 0),
@@ -262,42 +406,87 @@ describe('matchOrders', () => {
             );
         });
 
-        it('Should transfer correct amounts when right order fill amount deviates from amount derived by `Exchange.fillOrder`', async () => {
+        it('Should give right maker and right taker a favorable fee price when rounding', async () => {
             // Create orders to match
             const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
                 makerAddress: makerAddressLeft,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 0),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
                 feeRecipientAddress: feeRecipientAddressLeft,
             });
             const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
                 makerAddress: makerAddressRight,
                 makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
                 takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(4), 0),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 0),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(83), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(49), 0),
                 feeRecipientAddress: feeRecipientAddressRight,
+                makerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(10000), 0),
+                takerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(10000), 0),
             });
-            // TODO: These values will change after implementation of rounding up has been merged
+            // Note:
+            //  The maker/taker fee percentage paid on the right order differs because
+            //  they received different sale prices. The right maker pays a
+            //  fee slightly lower than the right taker.
             const expectedTransferAmounts = {
                 // Left Maker
-                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 0),
-                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(16), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
                 feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
                 // Right Maker
-                // Note:
-                //  For order [4,2] valid fill amounts through `Exchange.fillOrder` would be [2, 1] or [4, 2]
-                //  In this case we have fill amounts of [3, 1] which is attainable through
-                // `Exchange.matchOrders` but not `Exchange.fillOrder`
-                // Note:
-                //  The right maker fee differs from the right taker fee because their exchange rate differs.
-                //  The right maker always receives the better exchange and fee price.
-                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
-                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2), 0),
-                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(75), 16), // 75%
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(22), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(13), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(2650), 0), // 2650.6 rounded down tro 2650
                 // Taker
-                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(8), 0),
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(3), 0),
                 feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(2653), 0), // 2653.1 rounded down to 2653
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
+        it('Should give left maker and left taker a favorable fee price when rounding', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAddress: makerAddressLeft,
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(12), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(97), 0),
+                feeRecipientAddress: feeRecipientAddressLeft,
+                makerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(10000), 0),
+                takerFee: Web3Wrapper.toBaseUnitAmount(new BigNumber(10000), 0),
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAddress: makerAddressRight,
+                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                feeRecipientAddress: feeRecipientAddressRight,
+            });
+            // Note:
+            //  The maker/taker fee percentage paid on the left order differs because
+            //  they received different sale prices. The left maker pays a
+            //  fee slightly lower than the left taker.
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(11), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(9166), 0), // 9166.6 rounded down to 9166
+                // Right Maker
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(89), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(10), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(9175), 0), // 9175.2 rounded down to 9175
                 feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
             };
             // Match signedOrderLeft with signedOrderRight
@@ -311,6 +500,61 @@ describe('matchOrders', () => {
             );
         });
 
+        it('Should transfer correct amounts when right order fill amount deviates from amount derived by `Exchange.fillOrder`', async () => {
+            // Create orders to match
+            const signedOrderLeft = await orderFactoryLeft.newSignedOrderAsync({
+                makerAddress: makerAddressLeft,
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1000), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
+                feeRecipientAddress: feeRecipientAddressLeft,
+            });
+            const signedOrderRight = await orderFactoryRight.newSignedOrderAsync({
+                makerAddress: makerAddressRight,
+                makerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20TakerAssetAddress),
+                takerAssetData: assetDataUtils.encodeERC20AssetData(defaultERC20MakerAssetAddress),
+                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(2126), 0),
+                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(1063), 0),
+                feeRecipientAddress: feeRecipientAddressRight,
+            });
+            const expectedTransferAmounts = {
+                // Left Maker
+                amountSoldByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1000), 0),
+                amountBoughtByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
+                feePaidByLeftMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                // Right Maker
+                // Notes:
+                //  i.
+                //    The left order is fully filled by the right order, so the right maker must sell 1005 units of their asset to the left maker.
+                //    By selling 1005 units, the right maker should theoretically receive 502.5 units of the left maker's asset.
+                //    Since the transfer amount must be an integer, this value must be rounded down to 502 or up to 503.
+                //  ii.
+                //    If the right order were filled via `Exchange.fillOrder` the respective fill amounts would be [1004, 502] or [1006, 503].
+                //    It follows that we cannot trigger a sale of 1005 units of the right maker's asset through `Exchange.fillOrder`.
+                //  iii.
+                //    For an optimal match, the algorithm must choose either [1005, 502] or [1005, 503] as fill amounts for the right order.
+                //    The algorithm favors the right maker when the exchange rate must be rounded, so the final fill for the right order is [1005, 503].
+                //  iv.
+                //    The right maker fee differs from the right taker fee because their exchange rate differs.
+                //    The right maker always receives the better exchange and fee price.
+                amountSoldByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(1005), 0),
+                amountBoughtByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(503), 0),
+                feePaidByRightMaker: Web3Wrapper.toBaseUnitAmount(new BigNumber('47.2718720602069614'), 16), // 47.27%
+                // Taker
+                amountReceivedByTaker: Web3Wrapper.toBaseUnitAmount(new BigNumber(497), 0),
+                feePaidByTakerLeft: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 16), // 100%
+                feePaidByTakerRight: Web3Wrapper.toBaseUnitAmount(new BigNumber('47.3189087488240827'), 16), // 47.31%
+            };
+            // Match signedOrderLeft with signedOrderRight
+            await matchOrderTester.matchOrdersAndAssertEffectsAsync(
+                signedOrderLeft,
+                signedOrderRight,
+                takerAddress,
+                erc20BalancesByOwner,
+                erc721TokenIdsByOwner,
+                expectedTransferAmounts,
+            );
+        });
+
         const reentrancyTest = (functionNames: string[]) => {
             _.forEach(functionNames, async (functionName: string, functionId: number) => {
                 const description = `should not allow matchOrders to reenter the Exchange contract via ${functionName}`;
diff --git a/packages/contracts/test/exchange/signature_validator.ts b/packages/contracts/test/exchange/signature_validator.ts
index da2febfd8..5cc62e777 100644
--- a/packages/contracts/test/exchange/signature_validator.ts
+++ b/packages/contracts/test/exchange/signature_validator.ts
@@ -14,7 +14,7 @@ import { ValidatorContract } from '../../generated_contract_wrappers/validator';
 import { WalletContract } from '../../generated_contract_wrappers/wallet';
 import { addressUtils } from '../utils/address_utils';
 import { artifacts } from '../utils/artifacts';
-import { expectContractCallFailed, expectContractCallFailedWithoutReasonAsync } from '../utils/assertions';
+import { expectContractCallFailedAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { LogDecoder } from '../utils/log_decoder';
@@ -119,7 +119,7 @@ describe('MixinSignatureValidator', () => {
         it('should revert when signature is empty', async () => {
             const emptySignature = '0x';
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(
                     orderHashHex,
                     signedOrder.makerAddress,
@@ -133,7 +133,7 @@ describe('MixinSignatureValidator', () => {
             const unsupportedSignatureType = SignatureType.NSignatureTypes;
             const unsupportedSignatureHex = '0x' + Buffer.from([unsupportedSignatureType]).toString('hex');
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(
                     orderHashHex,
                     signedOrder.makerAddress,
@@ -146,7 +146,7 @@ describe('MixinSignatureValidator', () => {
         it('should revert when SignatureType=Illegal', async () => {
             const unsupportedSignatureHex = '0x' + Buffer.from([SignatureType.Illegal]).toString('hex');
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(
                     orderHashHex,
                     signedOrder.makerAddress,
@@ -173,7 +173,7 @@ describe('MixinSignatureValidator', () => {
             const signatureBuffer = Buffer.concat([fillerData, signatureType]);
             const signatureHex = ethUtil.bufferToHex(signatureBuffer);
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(
                     orderHashHex,
                     signedOrder.makerAddress,
@@ -339,7 +339,7 @@ describe('MixinSignatureValidator', () => {
                 ethUtil.toBuffer(`0x${SignatureType.Wallet}`),
             ]);
             const signatureHex = ethUtil.bufferToHex(signature);
-            await expectContractCallFailed(
+            await expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(
                     orderHashHex,
                     maliciousWallet.address,
@@ -385,7 +385,7 @@ describe('MixinSignatureValidator', () => {
             const signature = Buffer.concat([validatorAddress, signatureType]);
             const signatureHex = ethUtil.bufferToHex(signature);
             const orderHashHex = orderHashUtils.getOrderHashHex(signedOrder);
-            await expectContractCallFailed(
+            await expectContractCallFailedAsync(
                 signatureValidator.publicIsValidSignature.callAsync(orderHashHex, signerAddress, signatureHex),
                 RevertReason.ValidatorError,
             );
diff --git a/packages/contracts/test/extensions/forwarder.ts b/packages/contracts/test/extensions/forwarder.ts
index 18101d684..8424d01fd 100644
--- a/packages/contracts/test/extensions/forwarder.ts
+++ b/packages/contracts/test/extensions/forwarder.ts
@@ -12,7 +12,11 @@ import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
 import { ForwarderContract } from '../../generated_contract_wrappers/forwarder';
 import { WETH9Contract } from '../../generated_contract_wrappers/weth9';
 import { artifacts } from '../utils/artifacts';
-import { expectTransactionFailedAsync } from '../utils/assertions';
+import {
+    expectContractCreationFailedAsync,
+    expectTransactionFailedAsync,
+    sendTransactionResult,
+} from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { ERC20Wrapper } from '../utils/erc20_wrapper';
@@ -37,6 +41,7 @@ describe(ContractName.Forwarder, () => {
     let otherAddress: string;
     let defaultMakerAssetAddress: string;
     let zrxAssetData: string;
+    let wethAssetData: string;
 
     let weth: DummyERC20TokenContract;
     let zrxToken: DummyERC20TokenContract;
@@ -90,7 +95,7 @@ describe(ContractName.Forwarder, () => {
         weth = new DummyERC20TokenContract(wethContract.abi, wethContract.address, provider);
         erc20Wrapper.addDummyTokenContract(weth);
 
-        const wethAssetData = assetDataUtils.encodeERC20AssetData(wethContract.address);
+        wethAssetData = assetDataUtils.encodeERC20AssetData(wethContract.address);
         zrxAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
         const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
             artifacts.Exchange,
@@ -98,8 +103,7 @@ describe(ContractName.Forwarder, () => {
             txDefaults,
             zrxAssetData,
         );
-        const exchangeContract = new ExchangeContract(exchangeInstance.abi, exchangeInstance.address, provider);
-        exchangeWrapper = new ExchangeWrapper(exchangeContract, provider);
+        exchangeWrapper = new ExchangeWrapper(exchangeInstance, provider);
         await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
         await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, owner);
 
@@ -162,6 +166,27 @@ describe(ContractName.Forwarder, () => {
         await blockchainLifecycle.revertAsync();
     });
 
+    describe('constructor', () => {
+        it('should revert if assetProxy is unregistered', async () => {
+            const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
+                artifacts.Exchange,
+                provider,
+                txDefaults,
+                zrxAssetData,
+            );
+            return expectContractCreationFailedAsync(
+                (ForwarderContract.deployFrom0xArtifactAsync(
+                    artifacts.Forwarder,
+                    provider,
+                    txDefaults,
+                    exchangeInstance.address,
+                    zrxAssetData,
+                    wethAssetData,
+                ) as any) as sendTransactionResult,
+                RevertReason.UnregisteredAssetProxy,
+            );
+        });
+    });
     describe('marketSellOrdersWithEth without extra fees', () => {
         it('should fill a single order', async () => {
             const ordersWithoutFee = [orderWithoutFee];
diff --git a/packages/contracts/test/libraries/lib_bytes.ts b/packages/contracts/test/libraries/lib_bytes.ts
index 1c497a226..13640a761 100644
--- a/packages/contracts/test/libraries/lib_bytes.ts
+++ b/packages/contracts/test/libraries/lib_bytes.ts
@@ -9,7 +9,7 @@ import * as _ from 'lodash';
 
 import { TestLibBytesContract } from '../../generated_contract_wrappers/test_lib_bytes';
 import { artifacts } from '../utils/artifacts';
-import { expectContractCallFailed } from '../utils/assertions';
+import { expectContractCallFailedAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { typeEncodingUtils } from '../utils/type_encoding_utils';
@@ -41,6 +41,8 @@ describe('LibBytes', () => {
     const testBytes32B = '0x534877abd8443578526845cdfef020047528759477fedef87346527659aced32';
     const testUint256 = new BigNumber(testBytes32, 16);
     const testUint256B = new BigNumber(testBytes32B, 16);
+    const testBytes4 = '0xabcdef12';
+    const testByte = '0xab';
     let shortData: string;
     let shortTestBytes: string;
     let shortTestBytesAsBuffer: Buffer;
@@ -101,34 +103,47 @@ describe('LibBytes', () => {
 
     describe('popLastByte', () => {
         it('should revert if length is 0', async () => {
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicPopLastByte.callAsync(constants.NULL_BYTES),
                 RevertReason.LibBytesGreaterThanZeroLengthRequired,
             );
         });
-        it('should pop the last byte from the input and return it', async () => {
+        it('should pop the last byte from the input and return it when array holds more than 1 byte', async () => {
             const [newBytes, poppedByte] = await libBytes.publicPopLastByte.callAsync(byteArrayLongerThan32Bytes);
             const expectedNewBytes = byteArrayLongerThan32Bytes.slice(0, -2);
             const expectedPoppedByte = `0x${byteArrayLongerThan32Bytes.slice(-2)}`;
             expect(newBytes).to.equal(expectedNewBytes);
             expect(poppedByte).to.equal(expectedPoppedByte);
         });
+        it('should pop the last byte from the input and return it when array is exactly 1 byte', async () => {
+            const [newBytes, poppedByte] = await libBytes.publicPopLastByte.callAsync(testByte);
+            const expectedNewBytes = '0x';
+            expect(newBytes).to.equal(expectedNewBytes);
+            return expect(poppedByte).to.be.equal(testByte);
+        });
     });
 
     describe('popLast20Bytes', () => {
         it('should revert if length is less than 20', async () => {
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicPopLast20Bytes.callAsync(byteArrayShorterThan20Bytes),
                 RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
             );
         });
-        it('should pop the last 20 bytes from the input and return it', async () => {
+        it('should pop the last 20 bytes from the input and return it when array holds more than 20 bytes', async () => {
             const [newBytes, poppedAddress] = await libBytes.publicPopLast20Bytes.callAsync(byteArrayLongerThan32Bytes);
             const expectedNewBytes = byteArrayLongerThan32Bytes.slice(0, -40);
             const expectedPoppedAddress = `0x${byteArrayLongerThan32Bytes.slice(-40)}`;
             expect(newBytes).to.equal(expectedNewBytes);
             expect(poppedAddress).to.equal(expectedPoppedAddress);
         });
+        it('should pop the last 20 bytes from the input and return it when array is exactly 20 bytes', async () => {
+            const [newBytes, poppedAddress] = await libBytes.publicPopLast20Bytes.callAsync(testAddress);
+            const expectedNewBytes = '0x';
+            const expectedPoppedAddress = testAddress;
+            expect(newBytes).to.equal(expectedNewBytes);
+            expect(poppedAddress).to.equal(expectedPoppedAddress);
+        });
     });
 
     describe('equals', () => {
@@ -185,7 +200,7 @@ describe('LibBytes', () => {
 
     describe('deepCopyBytes', () => {
         it('should revert if dest is shorter than source', async () => {
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicDeepCopyBytes.callAsync(byteArrayShorterThan32Bytes, byteArrayLongerThan32Bytes),
                 RevertReason.LibBytesGreaterOrEqualToSourceBytesLengthRequired,
             );
@@ -238,7 +253,7 @@ describe('LibBytes', () => {
         it('should fail if the byte array is too short to hold an address', async () => {
             const shortByteArray = '0xabcdef';
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadAddress.callAsync(shortByteArray, offset),
                 RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
             );
@@ -246,7 +261,7 @@ describe('LibBytes', () => {
         it('should fail if the length between the offset and end of the byte array is too short to hold an address', async () => {
             const byteArray = testAddress;
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadAddress.callAsync(byteArray, badOffset),
                 RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
             );
@@ -282,7 +297,7 @@ describe('LibBytes', () => {
         });
         it('should fail if the byte array is too short to hold an address', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteAddress.callAsync(byteArrayShorterThan20Bytes, offset, testAddress),
                 RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
             );
@@ -290,7 +305,7 @@ describe('LibBytes', () => {
         it('should fail if the length between the offset and end of the byte array is too short to hold an address', async () => {
             const byteArray = byteArrayLongerThan32Bytes;
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteAddress.callAsync(byteArray, badOffset, testAddress),
                 RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
             );
@@ -303,7 +318,7 @@ describe('LibBytes', () => {
             const bytes32 = await libBytes.publicReadBytes32.callAsync(testBytes32, testBytes32Offset);
             return expect(bytes32).to.be.equal(testBytes32);
         });
-        it('should successfully read bytes32 when it is offset in the array)', async () => {
+        it('should successfully read bytes32 when it is offset in the array', async () => {
             const bytes32ByteArrayBuffer = ethUtil.toBuffer(testBytes32);
             const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes32ByteArrayBuffer]);
@@ -314,14 +329,14 @@ describe('LibBytes', () => {
         });
         it('should fail if the byte array is too short to hold a bytes32', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytes32.callAsync(byteArrayShorterThan32Bytes, offset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold a bytes32', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytes32.callAsync(testBytes32, badOffset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -357,7 +372,7 @@ describe('LibBytes', () => {
         });
         it('should fail if the byte array is too short to hold a bytes32', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteBytes32.callAsync(byteArrayShorterThan32Bytes, offset, testBytes32),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -365,7 +380,7 @@ describe('LibBytes', () => {
         it('should fail if the length between the offset and end of the byte array is too short to hold a bytes32', async () => {
             const byteArray = byteArrayLongerThan32Bytes;
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteBytes32.callAsync(byteArray, badOffset, testBytes32),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -393,7 +408,7 @@ describe('LibBytes', () => {
         });
         it('should fail if the byte array is too short to hold a uint256', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadUint256.callAsync(byteArrayShorterThan32Bytes, offset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -403,7 +418,7 @@ describe('LibBytes', () => {
             const testUint256AsBuffer = ethUtil.toBuffer(formattedTestUint256);
             const byteArray = ethUtil.bufferToHex(testUint256AsBuffer);
             const badOffset = new BigNumber(testUint256AsBuffer.byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadUint256.callAsync(byteArray, badOffset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -443,7 +458,7 @@ describe('LibBytes', () => {
         });
         it('should fail if the byte array is too short to hold a uint256', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteUint256.callAsync(byteArrayShorterThan32Bytes, offset, testUint256),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -451,7 +466,7 @@ describe('LibBytes', () => {
         it('should fail if the length between the offset and end of the byte array is too short to hold a uint256', async () => {
             const byteArray = byteArrayLongerThan32Bytes;
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteUint256.callAsync(byteArray, badOffset, testUint256),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -462,8 +477,9 @@ describe('LibBytes', () => {
         // AssertionError: expected promise to be rejected with an error including 'revert' but it was fulfilled with '0x08c379a0'
         it('should revert if byte array has a length < 4', async () => {
             const byteArrayLessThan4Bytes = '0x010101';
-            return expectContractCallFailed(
-                libBytes.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, new BigNumber(0)),
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, offset),
                 RevertReason.LibBytesGreaterOrEqualTo4LengthRequired,
             );
         });
@@ -472,6 +488,27 @@ describe('LibBytes', () => {
             const expectedFirst4Bytes = byteArrayLongerThan32Bytes.slice(0, 10);
             expect(first4Bytes).to.equal(expectedFirst4Bytes);
         });
+        it('should successfully read bytes4 when the bytes4 takes up the whole array', async () => {
+            const testBytes4Offset = new BigNumber(0);
+            const bytes4 = await libBytes.publicReadBytes4.callAsync(testBytes4, testBytes4Offset);
+            return expect(bytes4).to.be.equal(testBytes4);
+        });
+        it('should successfully read bytes4 when it is offset in the array', async () => {
+            const bytes4ByteArrayBuffer = ethUtil.toBuffer(testBytes4);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes4ByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testBytes4Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes4 = await libBytes.publicReadBytes4.callAsync(combinedByteArray, testBytes4Offset);
+            return expect(bytes4).to.be.equal(testBytes4);
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a bytes4', async () => {
+            const badOffset = new BigNumber(ethUtil.toBuffer(testBytes4).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes4.callAsync(testBytes4, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo4LengthRequired,
+            );
+        });
     });
 
     describe('readBytesWithLength', () => {
@@ -517,28 +554,28 @@ describe('LibBytes', () => {
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             // The length of the nested array is 32 bytes. By storing less than 32 bytes, a length cannot be read.
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, offset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
         it('should fail if we store a nested byte array length, without a nested byte array', async () => {
             const offset = new BigNumber(0);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytesWithLength.callAsync(testBytes32, offset),
                 RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArrayShorterThan32Bytes).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, badOffset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicReadBytesWithLength.callAsync(testBytes32, badOffset),
                 RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
             );
@@ -546,7 +583,7 @@ describe('LibBytes', () => {
     });
 
     describe('writeBytesWithLength', () => {
-        it('should successfully write short, nested array of bytes when it takes up the whole array)', async () => {
+        it('should successfully write short, nested array of bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
             const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
@@ -650,15 +687,15 @@ describe('LibBytes', () => {
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             const offset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(1));
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, offset, longData),
                 RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
         });
-        it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array)', async () => {
+        it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
             const badOffset = new BigNumber(ethUtil.toBuffer(shortTestBytesAsBuffer).byteLength);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, badOffset, shortData),
                 RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
             );
diff --git a/packages/contracts/test/multisig/asset_proxy_owner.ts b/packages/contracts/test/multisig/asset_proxy_owner.ts
index 9515941ff..299707512 100644
--- a/packages/contracts/test/multisig/asset_proxy_owner.ts
+++ b/packages/contracts/test/multisig/asset_proxy_owner.ts
@@ -1,4 +1,5 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
+import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import { LogWithDecodedArgs } from 'ethereum-types';
@@ -14,9 +15,11 @@ import { MixinAuthorizableContract } from '../../generated_contract_wrappers/mix
 import { TestAssetProxyOwnerContract } from '../../generated_contract_wrappers/test_asset_proxy_owner';
 import { artifacts } from '../utils/artifacts';
 import {
-    expectContractCallFailedWithoutReasonAsync,
-    expectContractCreationFailedWithoutReason,
+    expectContractCallFailedAsync,
+    expectContractCreationFailedAsync,
+    expectTransactionFailedAsync,
     expectTransactionFailedWithoutReasonAsync,
+    sendTransactionResult,
 } from '../utils/assertions';
 import { increaseTimeAndMineBlockAsync } from '../utils/block_timestamp';
 import { chaiSetup } from '../utils/chai_setup';
@@ -31,6 +34,7 @@ const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 describe('AssetProxyOwner', () => {
     let owners: string[];
     let authorized: string;
+    let notOwner: string;
     const REQUIRED_APPROVALS = new BigNumber(2);
     const SECONDS_TIME_LOCKED = new BigNumber(1000000);
 
@@ -48,7 +52,9 @@ describe('AssetProxyOwner', () => {
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
         owners = [accounts[0], accounts[1]];
-        const initialOwner = (authorized = accounts[0]);
+        authorized = accounts[2];
+        notOwner = accounts[3];
+        const initialOwner = accounts[0];
         erc20Proxy = await MixinAuthorizableContract.deployFrom0xArtifactAsync(
             artifacts.MixinAuthorizable,
             provider,
@@ -109,8 +115,8 @@ describe('AssetProxyOwner', () => {
         });
         it('should throw if a null address is included in assetProxyContracts', async () => {
             const assetProxyContractAddresses = [erc20Proxy.address, constants.NULL_ADDRESS];
-            return expectContractCreationFailedWithoutReason(
-                AssetProxyOwnerContract.deployFrom0xArtifactAsync(
+            return expectContractCreationFailedAsync(
+                (AssetProxyOwnerContract.deployFrom0xArtifactAsync(
                     artifacts.AssetProxyOwner,
                     provider,
                     txDefaults,
@@ -118,7 +124,8 @@ describe('AssetProxyOwner', () => {
                     assetProxyContractAddresses,
                     REQUIRED_APPROVALS,
                     SECONDS_TIME_LOCKED,
-                ),
+                ) as any) as sendTransactionResult,
+                RevertReason.InvalidAssetProxy,
             );
         });
     });
@@ -148,25 +155,6 @@ describe('AssetProxyOwner', () => {
         });
     });
 
-    describe('readBytes4', () => {
-        it('should revert if byte array has a length < 4', async () => {
-            const byteArrayLessThan4Bytes = '0x010101';
-            return expectContractCallFailedWithoutReasonAsync(
-                testAssetProxyOwner.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, new BigNumber(0)),
-            );
-        });
-        it('should return the first 4 bytes of a byte array of arbitrary length', async () => {
-            const byteArrayLongerThan32Bytes =
-                '0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef';
-            const first4Bytes = await testAssetProxyOwner.publicReadBytes4.callAsync(
-                byteArrayLongerThan32Bytes,
-                new BigNumber(0),
-            );
-            const expectedFirst4Bytes = byteArrayLongerThan32Bytes.slice(0, 10);
-            expect(first4Bytes).to.equal(expectedFirst4Bytes);
-        });
-    });
-
     describe('registerAssetProxy', () => {
         it('should throw if not called by multisig', async () => {
             const isRegistered = true;
@@ -284,8 +272,12 @@ describe('AssetProxyOwner', () => {
             await multiSigWrapper.confirmTransactionAsync(erc721AddAuthorizedAddressTxId, owners[1]);
             await increaseTimeAndMineBlockAsync(SECONDS_TIME_LOCKED.toNumber());
             await multiSigWrapper.executeTransactionAsync(registerAssetProxyTxId, owners[0]);
-            await multiSigWrapper.executeTransactionAsync(erc20AddAuthorizedAddressTxId, owners[0]);
-            await multiSigWrapper.executeTransactionAsync(erc721AddAuthorizedAddressTxId, owners[0]);
+            await multiSigWrapper.executeTransactionAsync(erc20AddAuthorizedAddressTxId, owners[0], {
+                gas: constants.MAX_EXECUTE_TRANSACTION_GAS,
+            });
+            await multiSigWrapper.executeTransactionAsync(erc721AddAuthorizedAddressTxId, owners[0], {
+                gas: constants.MAX_EXECUTE_TRANSACTION_GAS,
+            });
         });
 
         describe('validRemoveAuthorizedAddressAtIndexTx', () => {
@@ -300,8 +292,9 @@ describe('AssetProxyOwner', () => {
                 );
                 const log = submitTxRes.logs[0] as LogWithDecodedArgs<AssetProxyOwnerSubmissionEventArgs>;
                 const txId = log.args.transactionId;
-                return expectContractCallFailedWithoutReasonAsync(
+                return expectContractCallFailedAsync(
                     testAssetProxyOwner.testValidRemoveAuthorizedAddressAtIndexTx.callAsync(txId),
+                    RevertReason.InvalidFunctionSelector,
                 );
             });
 
@@ -335,8 +328,9 @@ describe('AssetProxyOwner', () => {
                 );
                 const log = submitTxRes.logs[0] as LogWithDecodedArgs<AssetProxyOwnerSubmissionEventArgs>;
                 const txId = log.args.transactionId;
-                return expectContractCallFailedWithoutReasonAsync(
+                return expectContractCallFailedAsync(
                     testAssetProxyOwner.testValidRemoveAuthorizedAddressAtIndexTx.callAsync(txId),
+                    RevertReason.UnregisteredAssetProxy,
                 );
             });
         });
@@ -355,10 +349,11 @@ describe('AssetProxyOwner', () => {
                 const log = res.logs[0] as LogWithDecodedArgs<AssetProxyOwnerSubmissionEventArgs>;
                 const txId = log.args.transactionId;
 
-                return expectTransactionFailedWithoutReasonAsync(
+                return expectTransactionFailedAsync(
                     testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
                         from: owners[1],
                     }),
+                    RevertReason.TxNotFullyConfirmed,
                 );
             });
 
@@ -377,10 +372,11 @@ describe('AssetProxyOwner', () => {
 
                 await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
 
-                return expectTransactionFailedWithoutReasonAsync(
+                return expectTransactionFailedAsync(
                     testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
                         from: owners[1],
                     }),
+                    RevertReason.UnregisteredAssetProxy,
                 );
             });
 
@@ -399,14 +395,18 @@ describe('AssetProxyOwner', () => {
 
                 await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
 
-                return expectTransactionFailedWithoutReasonAsync(
+                return expectTransactionFailedAsync(
                     testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
                         from: owners[1],
                     }),
+                    RevertReason.InvalidFunctionSelector,
                 );
             });
 
-            it('should execute removeAuthorizedAddressAtIndex for registered address if fully confirmed', async () => {
+            it('should execute removeAuthorizedAddressAtIndex for registered address if fully confirmed and called by owner', async () => {
+                const isAuthorizedBefore = await erc20Proxy.authorized.callAsync(authorized);
+                expect(isAuthorizedBefore).to.equal(true);
+
                 const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
                     authorized,
                     erc20Index,
@@ -429,8 +429,38 @@ describe('AssetProxyOwner', () => {
                 const isExecuted = tx[3];
                 expect(isExecuted).to.equal(true);
 
-                const isAuthorized = await erc20Proxy.authorized.callAsync(authorized);
-                expect(isAuthorized).to.equal(false);
+                const isAuthorizedAfter = await erc20Proxy.authorized.callAsync(authorized);
+                expect(isAuthorizedAfter).to.equal(false);
+            });
+
+            it('should execute removeAuthorizedAddressAtIndex for registered address if fully confirmed and called by non-owner', async () => {
+                const isAuthorizedBefore = await erc20Proxy.authorized.callAsync(authorized);
+                expect(isAuthorizedBefore).to.equal(true);
+
+                const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc20Index,
+                );
+                const submitRes = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const submitLog = submitRes.logs[0] as LogWithDecodedArgs<AssetProxyOwnerSubmissionEventArgs>;
+                const txId = submitLog.args.transactionId;
+
+                await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+
+                const execRes = await multiSigWrapper.executeRemoveAuthorizedAddressAtIndexAsync(txId, notOwner);
+                const execLog = execRes.logs[1] as LogWithDecodedArgs<AssetProxyOwnerExecutionEventArgs>;
+                expect(execLog.args.transactionId).to.be.bignumber.equal(txId);
+
+                const tx = await testAssetProxyOwner.transactions.callAsync(txId);
+                const isExecuted = tx[3];
+                expect(isExecuted).to.equal(true);
+
+                const isAuthorizedAfter = await erc20Proxy.authorized.callAsync(authorized);
+                expect(isAuthorizedAfter).to.equal(false);
             });
 
             it('should throw if already executed', async () => {
diff --git a/packages/contracts/test/multisig/multi_sig_with_time_lock.ts b/packages/contracts/test/multisig/multi_sig_with_time_lock.ts
index 8eeeeca6b..0b17c298b 100644
--- a/packages/contracts/test/multisig/multi_sig_with_time_lock.ts
+++ b/packages/contracts/test/multisig/multi_sig_with_time_lock.ts
@@ -1,14 +1,21 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
+import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import { LogWithDecodedArgs } from 'ethereum-types';
+import * as _ from 'lodash';
 
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_erc20_token';
 import {
+    MultiSigWalletWithTimeLockConfirmationEventArgs,
+    MultiSigWalletWithTimeLockConfirmationTimeSetEventArgs,
     MultiSigWalletWithTimeLockContract,
+    MultiSigWalletWithTimeLockExecutionEventArgs,
+    MultiSigWalletWithTimeLockExecutionFailureEventArgs,
     MultiSigWalletWithTimeLockSubmissionEventArgs,
 } from '../../generated_contract_wrappers/multi_sig_wallet_with_time_lock';
 import { artifacts } from '../utils/artifacts';
-import { expectTransactionFailedWithoutReasonAsync } from '../utils/assertions';
+import { expectTransactionFailedAsync, expectTransactionFailedWithoutReasonAsync } from '../utils/assertions';
 import { increaseTimeAndMineBlockAsync } from '../utils/block_timestamp';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
@@ -21,6 +28,7 @@ const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 // tslint:disable:no-unnecessary-type-assertion
 describe('MultiSigWalletWithTimeLock', () => {
     let owners: string[];
+    let notOwner: string;
     const REQUIRED_APPROVALS = new BigNumber(2);
     const SECONDS_TIME_LOCKED = new BigNumber(1000000);
 
@@ -32,7 +40,8 @@ describe('MultiSigWalletWithTimeLock', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        owners = [accounts[0], accounts[1]];
+        owners = [accounts[0], accounts[1], accounts[2]];
+        notOwner = accounts[3];
     });
 
     let multiSig: MultiSigWalletWithTimeLockContract;
@@ -45,6 +54,171 @@ describe('MultiSigWalletWithTimeLock', () => {
         await blockchainLifecycle.revertAsync();
     });
 
+    describe('external_call', () => {
+        it('should be internal', async () => {
+            const secondsTimeLocked = new BigNumber(0);
+            multiSig = await MultiSigWalletWithTimeLockContract.deployFrom0xArtifactAsync(
+                artifacts.MultiSigWalletWithTimeLock,
+                provider,
+                txDefaults,
+                owners,
+                REQUIRED_APPROVALS,
+                secondsTimeLocked,
+            );
+            expect(_.isUndefined((multiSig as any).external_call)).to.be.equal(true);
+        });
+    });
+    describe('confirmTransaction', () => {
+        let txId: BigNumber;
+        beforeEach(async () => {
+            const secondsTimeLocked = new BigNumber(0);
+            multiSig = await MultiSigWalletWithTimeLockContract.deployFrom0xArtifactAsync(
+                artifacts.MultiSigWalletWithTimeLock,
+                provider,
+                txDefaults,
+                owners,
+                REQUIRED_APPROVALS,
+                secondsTimeLocked,
+            );
+            multiSigWrapper = new MultiSigWrapper(multiSig, provider);
+            const destination = notOwner;
+            const data = constants.NULL_BYTES;
+            const txReceipt = await multiSigWrapper.submitTransactionAsync(destination, data, owners[0]);
+            txId = (txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockSubmissionEventArgs>).args
+                .transactionId;
+        });
+        it('should revert if called by a non-owner', async () => {
+            await expectTransactionFailedWithoutReasonAsync(multiSigWrapper.confirmTransactionAsync(txId, notOwner));
+        });
+        it('should revert if transaction does not exist', async () => {
+            const nonexistentTxId = new BigNumber(123456789);
+            await expectTransactionFailedWithoutReasonAsync(
+                multiSigWrapper.confirmTransactionAsync(nonexistentTxId, owners[1]),
+            );
+        });
+        it('should revert if transaction is already confirmed by caller', async () => {
+            await expectTransactionFailedWithoutReasonAsync(multiSigWrapper.confirmTransactionAsync(txId, owners[0]));
+        });
+        it('should confirm transaction for caller and log a Confirmation event', async () => {
+            const txReceipt = await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            const log = txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockConfirmationEventArgs>;
+            expect(log.event).to.be.equal('Confirmation');
+            expect(log.args.sender).to.be.equal(owners[1]);
+            expect(log.args.transactionId).to.be.bignumber.equal(txId);
+        });
+        it('should revert if fully confirmed', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await expectTransactionFailedAsync(
+                multiSigWrapper.confirmTransactionAsync(txId, owners[2]),
+                RevertReason.TxFullyConfirmed,
+            );
+        });
+        it('should set the confirmation time of the transaction if it becomes fully confirmed', async () => {
+            const txReceipt = await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            const blockNum = await web3Wrapper.getBlockNumberAsync();
+            const timestamp = new BigNumber(await web3Wrapper.getBlockTimestampAsync(blockNum));
+            const log = txReceipt.logs[1] as LogWithDecodedArgs<MultiSigWalletWithTimeLockConfirmationTimeSetEventArgs>;
+            expect(log.args.confirmationTime).to.be.bignumber.equal(timestamp);
+            expect(log.args.transactionId).to.be.bignumber.equal(txId);
+        });
+    });
+    describe('executeTransaction', () => {
+        let txId: BigNumber;
+        const secondsTimeLocked = new BigNumber(1000000);
+        beforeEach(async () => {
+            multiSig = await MultiSigWalletWithTimeLockContract.deployFrom0xArtifactAsync(
+                artifacts.MultiSigWalletWithTimeLock,
+                provider,
+                txDefaults,
+                owners,
+                REQUIRED_APPROVALS,
+                secondsTimeLocked,
+            );
+            multiSigWrapper = new MultiSigWrapper(multiSig, provider);
+            const destination = notOwner;
+            const data = constants.NULL_BYTES;
+            const txReceipt = await multiSigWrapper.submitTransactionAsync(destination, data, owners[0]);
+            txId = (txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockSubmissionEventArgs>).args
+                .transactionId;
+        });
+        it('should revert if transaction has not been fully confirmed', async () => {
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            await expectTransactionFailedAsync(
+                multiSigWrapper.executeTransactionAsync(txId, owners[1]),
+                RevertReason.TxNotFullyConfirmed,
+            );
+        });
+        it('should revert if time lock has not passed', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await expectTransactionFailedAsync(
+                multiSigWrapper.executeTransactionAsync(txId, owners[1]),
+                RevertReason.TimeLockIncomplete,
+            );
+        });
+        it('should execute a transaction and log an Execution event if successful and called by owner', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            const txReceipt = await multiSigWrapper.executeTransactionAsync(txId, owners[1]);
+            const log = txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockExecutionEventArgs>;
+            expect(log.event).to.be.equal('Execution');
+            expect(log.args.transactionId).to.be.bignumber.equal(txId);
+        });
+        it('should execute a transaction and log an Execution event if successful and called by non-owner', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            const txReceipt = await multiSigWrapper.executeTransactionAsync(txId, notOwner);
+            const log = txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockExecutionEventArgs>;
+            expect(log.event).to.be.equal('Execution');
+            expect(log.args.transactionId).to.be.bignumber.equal(txId);
+        });
+        it('should revert if a required confirmation is revoked before executeTransaction is called', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            await multiSigWrapper.revokeConfirmationAsync(txId, owners[0]);
+            await expectTransactionFailedAsync(
+                multiSigWrapper.executeTransactionAsync(txId, owners[1]),
+                RevertReason.TxNotFullyConfirmed,
+            );
+        });
+        it('should revert if transaction has been executed', async () => {
+            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            const txReceipt = await multiSigWrapper.executeTransactionAsync(txId, owners[1]);
+            const log = txReceipt.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockExecutionEventArgs>;
+            expect(log.args.transactionId).to.be.bignumber.equal(txId);
+            await expectTransactionFailedWithoutReasonAsync(multiSigWrapper.executeTransactionAsync(txId, owners[1]));
+        });
+        it("should log an ExecutionFailure event and not update the transaction's execution state if unsuccessful", async () => {
+            const contractWithoutFallback = await DummyERC20TokenContract.deployFrom0xArtifactAsync(
+                artifacts.DummyERC20Token,
+                provider,
+                txDefaults,
+                constants.DUMMY_TOKEN_NAME,
+                constants.DUMMY_TOKEN_SYMBOL,
+                constants.DUMMY_TOKEN_DECIMALS,
+                constants.DUMMY_TOKEN_TOTAL_SUPPLY,
+            );
+            const data = constants.NULL_BYTES;
+            const value = new BigNumber(10);
+            const submissionTxReceipt = await multiSigWrapper.submitTransactionAsync(
+                contractWithoutFallback.address,
+                data,
+                owners[0],
+                { value },
+            );
+            const newTxId = (submissionTxReceipt.logs[0] as LogWithDecodedArgs<
+                MultiSigWalletWithTimeLockSubmissionEventArgs
+            >).args.transactionId;
+            await multiSigWrapper.confirmTransactionAsync(newTxId, owners[1]);
+            await increaseTimeAndMineBlockAsync(secondsTimeLocked.toNumber());
+            const txReceipt = await multiSigWrapper.executeTransactionAsync(newTxId, owners[1]);
+            const executionFailureLog = txReceipt.logs[0] as LogWithDecodedArgs<
+                MultiSigWalletWithTimeLockExecutionFailureEventArgs
+            >;
+            expect(executionFailureLog.event).to.be.equal('ExecutionFailure');
+            expect(executionFailureLog.args.transactionId).to.be.bignumber.equal(newTxId);
+        });
+    });
     describe('changeTimeLock', () => {
         describe('initially non-time-locked', async () => {
             before(async () => {
@@ -78,8 +252,9 @@ describe('MultiSigWalletWithTimeLock', () => {
                 const res = await multiSigWrapper.submitTransactionAsync(destination, changeTimeLockData, owners[0]);
                 const log = res.logs[0] as LogWithDecodedArgs<MultiSigWalletWithTimeLockSubmissionEventArgs>;
                 const txId = log.args.transactionId;
-                return expectTransactionFailedWithoutReasonAsync(
+                return expectTransactionFailedAsync(
                     multiSig.executeTransaction.sendTransactionAsync(txId, { from: owners[0] }),
+                    RevertReason.TxNotFullyConfirmed,
                 );
             });
 
@@ -94,7 +269,10 @@ describe('MultiSigWalletWithTimeLock', () => {
                 expect(confirmRes.logs).to.have.length(2);
 
                 const blockNum = await web3Wrapper.getBlockNumberAsync();
-                const blockInfo = await web3Wrapper.getBlockAsync(blockNum);
+                const blockInfo = await web3Wrapper.getBlockIfExistsAsync(blockNum);
+                if (_.isUndefined(blockInfo)) {
+                    throw new Error(`Unexpectedly failed to fetch block at #${blockNum}`);
+                }
                 const timestamp = new BigNumber(blockInfo.timestamp);
                 const confirmationTimeBigNum = new BigNumber(await multiSig.confirmationTimes.callAsync(txId));
 
@@ -147,8 +325,9 @@ describe('MultiSigWalletWithTimeLock', () => {
             });
 
             it('should throw if it has enough confirmations but is not past the time lock', async () => {
-                return expectTransactionFailedWithoutReasonAsync(
+                return expectTransactionFailedAsync(
                     multiSig.executeTransaction.sendTransactionAsync(txId, { from: owners[0] }),
+                    RevertReason.TimeLockIncomplete,
                 );
             });
 
diff --git a/packages/contracts/test/tokens/unlimited_allowance_token.ts b/packages/contracts/test/tokens/unlimited_allowance_token.ts
index f2725b408..63680fe9b 100644
--- a/packages/contracts/test/tokens/unlimited_allowance_token.ts
+++ b/packages/contracts/test/tokens/unlimited_allowance_token.ts
@@ -5,7 +5,7 @@ import * as chai from 'chai';
 
 import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_erc20_token';
 import { artifacts } from '../utils/artifacts';
-import { expectContractCallFailed } from '../utils/assertions';
+import { expectContractCallFailedAsync } from '../utils/assertions';
 import { chaiSetup } from '../utils/chai_setup';
 import { constants } from '../utils/constants';
 import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
@@ -54,7 +54,7 @@ describe('UnlimitedAllowanceToken', () => {
         it('should throw if owner has insufficient balance', async () => {
             const ownerBalance = await token.balanceOf.callAsync(owner);
             const amountToTransfer = ownerBalance.plus(1);
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 token.transfer.callAsync(spender, amountToTransfer, { from: owner }),
                 RevertReason.Erc20InsufficientBalance,
             );
@@ -93,7 +93,7 @@ describe('UnlimitedAllowanceToken', () => {
                 await token.approve.sendTransactionAsync(spender, amountToTransfer, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 token.transferFrom.callAsync(owner, spender, amountToTransfer, {
                     from: spender,
                 }),
@@ -109,7 +109,7 @@ describe('UnlimitedAllowanceToken', () => {
             const isSpenderAllowanceInsufficient = spenderAllowance.cmp(amountToTransfer) < 0;
             expect(isSpenderAllowanceInsufficient).to.be.true();
 
-            return expectContractCallFailed(
+            return expectContractCallFailedAsync(
                 token.transferFrom.callAsync(owner, spender, amountToTransfer, {
                     from: spender,
                 }),
diff --git a/packages/contracts/test/utils/artifacts.ts b/packages/contracts/test/utils/artifacts.ts
index 5ddb5cc7f..53f2a4e4e 100644
--- a/packages/contracts/test/utils/artifacts.ts
+++ b/packages/contracts/test/utils/artifacts.ts
@@ -4,6 +4,7 @@ import * as AssetProxyOwner from '../../artifacts/AssetProxyOwner.json';
 import * as DummyERC20Token from '../../artifacts/DummyERC20Token.json';
 import * as DummyERC721Receiver from '../../artifacts/DummyERC721Receiver.json';
 import * as DummyERC721Token from '../../artifacts/DummyERC721Token.json';
+import * as DummyMultipleReturnERC20Token from '../../artifacts/DummyMultipleReturnERC20Token.json';
 import * as DummyNoReturnERC20Token from '../../artifacts/DummyNoReturnERC20Token.json';
 import * as ERC20Proxy from '../../artifacts/ERC20Proxy.json';
 import * as ERC721Proxy from '../../artifacts/ERC721Proxy.json';
@@ -37,6 +38,7 @@ export const artifacts = {
     DummyERC20Token: (DummyERC20Token as any) as ContractArtifact,
     DummyERC721Receiver: (DummyERC721Receiver as any) as ContractArtifact,
     DummyERC721Token: (DummyERC721Token as any) as ContractArtifact,
+    DummyMultipleReturnERC20Token: (DummyMultipleReturnERC20Token as any) as ContractArtifact,
     DummyNoReturnERC20Token: (DummyNoReturnERC20Token as any) as ContractArtifact,
     ERC20Proxy: (ERC20Proxy as any) as ContractArtifact,
     ERC721Proxy: (ERC721Proxy as any) as ContractArtifact,
diff --git a/packages/contracts/test/utils/assertions.ts b/packages/contracts/test/utils/assertions.ts
index 61df800c8..3361a751a 100644
--- a/packages/contracts/test/utils/assertions.ts
+++ b/packages/contracts/test/utils/assertions.ts
@@ -159,7 +159,7 @@ export async function expectTransactionFailedWithoutReasonAsync(p: sendTransacti
  * @returns a new Promise which will reject if the conditions are not met and
  * otherwise resolve with no value.
  */
-export async function expectContractCallFailed<T>(p: Promise<T>, reason: RevertReason): Promise<void> {
+export async function expectContractCallFailedAsync<T>(p: Promise<T>, reason: RevertReason): Promise<void> {
     return expect(p).to.be.rejectedWith(reason);
 }
 
@@ -180,7 +180,20 @@ export async function expectContractCallFailedWithoutReasonAsync<T>(p: Promise<T
  * @returns a new Promise which will reject if the conditions are not met and
  * otherwise resolve with no value.
  */
-export async function expectContractCreationFailedWithoutReason<T>(p: Promise<T>): Promise<void> {
+export async function expectContractCreationFailedAsync<T>(
+    p: sendTransactionResult,
+    reason: RevertReason,
+): Promise<void> {
+    return expectTransactionFailedAsync(p, reason);
+}
+
+/**
+ * Resolves if the contract creation/deployment fails without a revert reason.
+ * @param p a Promise resulting from a contract creation/deployment
+ * @returns a new Promise which will reject if the conditions are not met and
+ * otherwise resolve with no value.
+ */
+export async function expectContractCreationFailedWithoutReasonAsync<T>(p: Promise<T>): Promise<void> {
     const errMessage = await _getTransactionFailedErrorMessageAsync();
     return expect(p).to.be.rejectedWith(errMessage);
 }
diff --git a/packages/contracts/test/utils/block_timestamp.ts b/packages/contracts/test/utils/block_timestamp.ts
index 1159792c4..66c13eed1 100644
--- a/packages/contracts/test/utils/block_timestamp.ts
+++ b/packages/contracts/test/utils/block_timestamp.ts
@@ -35,6 +35,9 @@ export async function increaseTimeAndMineBlockAsync(seconds: number): Promise<nu
  * @returns a new Promise which will resolve with the timestamp in seconds.
  */
 export async function getLatestBlockTimestampAsync(): Promise<number> {
-    const currentBlock = await web3Wrapper.getBlockAsync('latest');
-    return currentBlock.timestamp;
+    const currentBlockIfExists = await web3Wrapper.getBlockIfExistsAsync('latest');
+    if (_.isUndefined(currentBlockIfExists)) {
+        throw new Error(`Unable to fetch latest block.`);
+    }
+    return currentBlockIfExists.timestamp;
 }
diff --git a/packages/contracts/test/utils/constants.ts b/packages/contracts/test/utils/constants.ts
index ee4378d2e..b9ba8ccb9 100644
--- a/packages/contracts/test/utils/constants.ts
+++ b/packages/contracts/test/utils/constants.ts
@@ -60,6 +60,7 @@ export const constants = {
         'MARKET_SELL_ORDERS',
         'MATCH_ORDERS',
         'CANCEL_ORDER',
+        'BATCH_CANCEL_ORDERS',
         'CANCEL_ORDERS_UP_TO',
         'SET_SIGNATURE_VALIDATOR_APPROVAL',
     ],
diff --git a/packages/contracts/test/utils/multi_sig_wrapper.ts b/packages/contracts/test/utils/multi_sig_wrapper.ts
index e0c27b839..e12a58695 100644
--- a/packages/contracts/test/utils/multi_sig_wrapper.ts
+++ b/packages/contracts/test/utils/multi_sig_wrapper.ts
@@ -6,7 +6,6 @@ import * as _ from 'lodash';
 import { AssetProxyOwnerContract } from '../../generated_contract_wrappers/asset_proxy_owner';
 import { MultiSigWalletContract } from '../../generated_contract_wrappers/multi_sig_wallet';
 
-import { constants } from './constants';
 import { LogDecoder } from './log_decoder';
 
 export class MultiSigWrapper {
@@ -36,10 +35,19 @@ export class MultiSigWrapper {
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
     }
-    public async executeTransactionAsync(txId: BigNumber, from: string): Promise<TransactionReceiptWithDecodedLogs> {
+    public async revokeConfirmationAsync(txId: BigNumber, from: string): Promise<TransactionReceiptWithDecodedLogs> {
+        const txHash = await this._multiSig.revokeConfirmation.sendTransactionAsync(txId, { from });
+        const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
+        return tx;
+    }
+    public async executeTransactionAsync(
+        txId: BigNumber,
+        from: string,
+        opts: { gas?: number } = {},
+    ): Promise<TransactionReceiptWithDecodedLogs> {
         const txHash = await this._multiSig.executeTransaction.sendTransactionAsync(txId, {
             from,
-            gas: constants.MAX_EXECUTE_TRANSACTION_GAS,
+            gas: opts.gas,
         });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
@@ -52,7 +60,6 @@ export class MultiSigWrapper {
         const txHash = await (this
             ._multiSig as AssetProxyOwnerContract).executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
             from,
-            gas: constants.MAX_EXECUTE_TRANSACTION_GAS,
         });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
diff --git a/packages/contracts/test/utils/web3_wrapper.ts b/packages/contracts/test/utils/web3_wrapper.ts
index acb3103b7..d1cd3d387 100644
--- a/packages/contracts/test/utils/web3_wrapper.ts
+++ b/packages/contracts/test/utils/web3_wrapper.ts
@@ -1,5 +1,5 @@
 import { devConstants, env, EnvVars, web3Factory } from '@0xproject/dev-utils';
-import { prependSubprovider } from '@0xproject/subproviders';
+import { prependSubprovider, Web3ProviderEngine } from '@0xproject/subproviders';
 import { logUtils } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as _ from 'lodash';
@@ -47,7 +47,7 @@ const ganacheConfigs = {
 };
 const providerConfigs = testProvider === ProviderType.Ganache ? ganacheConfigs : gethConfigs;
 
-export const provider = web3Factory.getRpcProvider(providerConfigs);
+export const provider: Web3ProviderEngine = web3Factory.getRpcProvider(providerConfigs);
 const isCoverageEnabled = env.parseBoolean(EnvVars.SolidityCoverage);
 const isProfilerEnabled = env.parseBoolean(EnvVars.SolidityProfiler);
 const isRevertTraceEnabled = env.parseBoolean(EnvVars.SolidityRevertTrace);
diff --git a/packages/contracts/tsconfig.json b/packages/contracts/tsconfig.json
index 86b33ede7..5fd4c5331 100644
--- a/packages/contracts/tsconfig.json
+++ b/packages/contracts/tsconfig.json
@@ -2,13 +2,11 @@
     "extends": "../../tsconfig",
     "compilerOptions": {
         "outDir": "lib",
-        "baseUrl": ".",
-        "declaration": false,
-        "allowJs": true
+        "rootDir": "."
     },
     "include": [
         "./globals.d.ts",
-        "./contract_wrappers",
+        "./generated_contract_wrappers",
         "./src/**/*",
         "./utils/**/*",
         "./test/**/*",