3 files changed, 14 insertions, 5 deletions
diff --git a/packages/base-contract/CHANGELOG.json b/packages/base-contract/CHANGELOG.json
index 8403d824b..fba072011 100644
--- a/packages/base-contract/CHANGELOG.json
+++ b/packages/base-contract/CHANGELOG.json
@@ -1,5 +1,14 @@
 [
     {
+        "version": "3.0.0",
+        "changes": [
+            {
+                "note": "Change the way we detect BN to work with the newest ethers.js",
+                "pr": 1069
+            }
+        ]
+    },
+    {
         "timestamp": 1537907159,
         "version": "2.0.5",
         "changes": [
diff --git a/packages/base-contract/package.json b/packages/base-contract/package.json
index 3bba0e81b..b4047691c 100644
--- a/packages/base-contract/package.json
+++ b/packages/base-contract/package.json
@@ -44,7 +44,7 @@
         "@0xproject/utils": "^1.0.11",
         "@0xproject/web3-wrapper": "^3.0.1",
         "ethereum-types": "^1.0.8",
-        "ethers": "3.0.22",
+        "ethers": "^4.0.0-beta.14",
         "lodash": "^4.17.5"
     },
     "publishConfig": {
diff --git a/packages/base-contract/src/index.ts b/packages/base-contract/src/index.ts
index 12f974445..90e576c24 100644
--- a/packages/base-contract/src/index.ts
+++ b/packages/base-contract/src/index.ts
@@ -61,7 +61,7 @@ export class BaseContract {
         }
     }
     protected static _bnToBigNumber(_type: string, value: any): any {
-        return _.isObject(value) && value._bn ? new BigNumber(value.toString()) : value;
+        return _.isObject(value) && value._hex ? new BigNumber(value.toString()) : value;
     }
     protected static async _applyDefaultsToTxDataAsync<T extends Partial<TxData | TxDataPayable>>(
         txData: T,
@@ -87,10 +87,10 @@ export class BaseContract {
     // if it overflows the corresponding Solidity type, there is a bug in the
     // encoder, or the encoder performs unsafe type coercion.
     public static strictArgumentEncodingCheck(inputAbi: DataItem[], args: any[]): void {
-        const coder = ethers.utils.AbiCoder.defaultCoder;
+        const coder = new ethers.AbiCoder();
         const params = abiUtils.parseEthersParams(inputAbi);
-        const rawEncoded = coder.encode(params.names, params.types, args);
-        const rawDecoded = coder.decode(params.names, params.types, rawEncoded);
+        const rawEncoded = coder.encode(inputAbi, args);
+        const rawDecoded = coder.decode(inputAbi, rawEncoded);
         for (let i = 0; i < rawDecoded.length; i++) {
             const original = args[i];
             const decoded = rawDecoded[i];