diff --git a/.solcover.js b/.solcover.js
index 0b4dd9498..9833f6247 100644
--- a/.solcover.js
+++ b/.solcover.js
@@ -5,7 +5,6 @@ module.exports = {
     'Migrations.sol',
     'mocks',
     'external',
-    'core/exchange-wrappers/ZeroExExchangeWrapper.sol',
-    'core/exchange-wrappers/lib/ZeroExOrderDataHandler.sol'
+    'core/exchange-wrappers/ZeroExExchangeWrapper.sol'
   ],
 };
diff --git a/contracts/core/exchange-wrappers/lib/ZeroExOrderDataHandler.sol b/contracts/core/exchange-wrappers/lib/ZeroExOrderDataHandler.sol
index f937f9193..efd4b50f8 100644
--- a/contracts/core/exchange-wrappers/lib/ZeroExOrderDataHandler.sol
+++ b/contracts/core/exchange-wrappers/lib/ZeroExOrderDataHandler.sol
@@ -79,7 +79,7 @@ library ZeroExOrderDataHandler {
         returns(address)
     {
         // Ensure that the asset is ERC20
-        require(ERC20_SELECTOR == _assetData.readBytes4(0));
+        require(_assetData.readBytes4(0) == ERC20_SELECTOR);
 
         // Return address
         return address(_assetData.readBytes32(4));