diff --git a/lib/utils/prototypes.js b/lib/utils/prototypes.js
index 014449e..e50d95c 100644
--- a/lib/utils/prototypes.js
+++ b/lib/utils/prototypes.js
@@ -69,7 +69,7 @@ Object.defineProperty(Array.prototype, 'extend', {
 
 Object.defineProperty(Object, 'isObject', {
   value: function (obj) {
-    return (obj != null && typeof obj === 'object' &&
+    return (obj !== null && typeof obj === 'object' &&
     Object.prototype.toString.call(obj) === '[object Object]')
   }
 })