9 files changed, 32 insertions, 27 deletions
diff --git a/packages/0x.js/test/utils/constants.ts b/packages/0x.js/test/utils/constants.ts
index 3b74fa863..cf030259c 100644
--- a/packages/0x.js/test/utils/constants.ts
+++ b/packages/0x.js/test/utils/constants.ts
@@ -6,5 +6,4 @@ export const constants = {
     KOVAN_RPC_URL: 'https://kovan.infura.io/',
     ROPSTEN_RPC_URL: 'https://ropsten.infura.io/',
     ZRX_DECIMALS: 18,
-    NULL_BYTES: '0x',
 };
diff --git a/packages/contracts/test/token_registry.ts b/packages/contracts/test/token_registry.ts
index 12fc52dbc..4c404176b 100644
--- a/packages/contracts/test/token_registry.ts
+++ b/packages/contracts/test/token_registry.ts
@@ -1,6 +1,6 @@
 import { ZeroEx } from '0x.js';
 import { BlockchainLifecycle, devConstants, web3Factory } from '@0xproject/dev-utils';
-import { BigNumber } from '@0xproject/utils';
+import { BigNumber, NULL_BYTES } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 import ethUtil = require('ethereumjs-util');
@@ -66,8 +66,8 @@ describe('TokenRegistry', () => {
         name: '',
         symbol: '',
         decimals: 0,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     };
 
     describe('addToken', () => {
diff --git a/packages/contracts/util/constants.ts b/packages/contracts/util/constants.ts
index 9bb090a2a..d1152e683 100644
--- a/packages/contracts/util/constants.ts
+++ b/packages/contracts/util/constants.ts
@@ -4,7 +4,6 @@ const DUMMY_TOKEN_DECIMALS = 18;
 const DUMMY_TOKEN_TOTAL_SUPPLY = 0;
 
 export const constants = {
-    NULL_BYTES: '0x',
     INVALID_OPCODE: 'invalid opcode',
     REVERT: 'revert',
     TESTRPC_NETWORK_ID: 50,
diff --git a/packages/migrations/src/migration.ts b/packages/migrations/src/migration.ts
index be899cc65..4827328fc 100644
--- a/packages/migrations/src/migration.ts
+++ b/packages/migrations/src/migration.ts
@@ -1,10 +1,8 @@
 import { Deployer } from '@0xproject/deployer';
-import { BigNumber } from '@0xproject/utils';
+import { BigNumber, NULL_BYTES } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as _ from 'lodash';
 
-import { constants } from './utils/constants';
-
 import { ContractName } from './types';
 import { tokenInfo } from './utils/token_info';
 
@@ -51,8 +49,8 @@ export const runMigrationsAsync = async (deployer: Deployer) => {
         '0x Protocol Token',
         'ZRX',
         18,
-        constants.NULL_BYTES,
-        constants.NULL_BYTES,
+        NULL_BYTES,
+        NULL_BYTES,
         {
             from: owner,
             gas: addTokenGasEstimate,
@@ -63,8 +61,8 @@ export const runMigrationsAsync = async (deployer: Deployer) => {
         'Ether Token',
         'WETH',
         18,
-        constants.NULL_BYTES,
-        constants.NULL_BYTES,
+        NULL_BYTES,
+        NULL_BYTES,
         {
             from: owner,
             gas: addTokenGasEstimate,
diff --git a/packages/migrations/src/utils/constants.ts b/packages/migrations/src/utils/constants.ts
deleted file mode 100644
index 8871a470d..000000000
--- a/packages/migrations/src/utils/constants.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-export const constants = {
-    NULL_BYTES: '0x',
-};
diff --git a/packages/migrations/src/utils/token_info.ts b/packages/migrations/src/utils/token_info.ts
index f2ca3e8b3..968665c7d 100644
--- a/packages/migrations/src/utils/token_info.ts
+++ b/packages/migrations/src/utils/token_info.ts
@@ -1,41 +1,41 @@
-import { Token } from '../types';
+import { NULL_BYTES } from '@0xproject/utils';
 
-import { constants } from './constants';
+import { Token } from '../types';
 
 export const tokenInfo: Token[] = [
     {
         name: 'Augur Reputation Token',
         symbol: 'REP',
         decimals: 18,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     },
     {
         name: 'Digix DAO Token',
         symbol: 'DGD',
         decimals: 18,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     },
     {
         name: 'Golem Network Token',
         symbol: 'GNT',
         decimals: 18,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     },
     {
         name: 'MakerDAO',
         symbol: 'MKR',
         decimals: 18,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     },
     {
         name: 'Melon Token',
         symbol: 'MLN',
         decimals: 18,
-        ipfsHash: constants.NULL_BYTES,
-        swarmHash: constants.NULL_BYTES,
+        ipfsHash: NULL_BYTES,
+        swarmHash: NULL_BYTES,
     },
 ];
diff --git a/packages/utils/CHANGELOG.json b/packages/utils/CHANGELOG.json
index 0c71963c3..3ba1f7d01 100644
--- a/packages/utils/CHANGELOG.json
+++ b/packages/utils/CHANGELOG.json
@@ -1,5 +1,14 @@
 [
     {
+        "version": "0.5.1",
+        "changes": [
+            {
+                "note": "Export NULL_BYTES constant",
+                "pr": 500
+            }
+        ]
+    },
+    {
         "version": "0.5.0",
         "changes": [
             {
diff --git a/packages/utils/src/constants.ts b/packages/utils/src/constants.ts
new file mode 100644
index 000000000..2894d4747
--- /dev/null
+++ b/packages/utils/src/constants.ts
@@ -0,0 +1 @@
+export const NULL_BYTES = '0x';
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index 0da4b265d..75c096ee6 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -6,3 +6,5 @@ export { BigNumber } from './configured_bignumber';
 export { AbiDecoder } from './abi_decoder';
 export { logUtils } from './log_utils';
 export { abiUtils } from './abi_utils';
+
+export { NULL_BYTES } from './constants';