diff --git a/lib/utils.js b/lib/utils.js
index 8c2736bccd..f0f90432c5 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -13,7 +13,7 @@ var toString = Object.prototype.toString;
  * @returns {boolean} True if value is an Array, otherwise false
  */
 function isArray(val) {
-  return toString.call(val) === '[object Array]';
+  return Array.isArray(val);
 }
 
 /**