diff --git a/packages/web3-eth-contract/src/index.js b/packages/web3-eth-contract/src/index.js
index 64aba3367cd..e63997982ee 100644
--- a/packages/web3-eth-contract/src/index.js
+++ b/packages/web3-eth-contract/src/index.js
@@ -66,8 +66,8 @@ var Contract = function Contract(jsonInterface, address, options) {
         throw new Error('Please use the "new" keyword to instantiate a web3.eth.contract() object!');
     }
 
-    if(!jsonInterface || !(jsonInterface instanceof Array)) {
-        throw new Error('You must provide the json interface of the contract when instatiating a contract object.');
+    if(!jsonInterface || !(Array.isArray(jsonInterface))) {
+        throw new Error('You must provide the json interface of the contract when instantiating a contract object.');
     }
 
     // add custom send Methods