diff --git a/lib/utils/prototypes.js b/lib/utils/prototypes.js
index af3cacb..cbff179 100644
--- a/lib/utils/prototypes.js
+++ b/lib/utils/prototypes.js
@@ -58,6 +58,7 @@ Object.defineProperty(Object, 'isObject', {
   enumerable: false,
   writable: true,
   value: function (obj) {
-    return ((!!obj) && (obj.constructor === Object))
+    return (obj != null && typeof obj === 'object' &&
+    Object.prototype.toString.call(obj) === '[object Object]')
   }
 })