diff --git a/underscore.js b/underscore.js
index 6bf375ed8..6bd1ee3ca 100644
--- a/underscore.js
+++ b/underscore.js
@@ -23,11 +23,10 @@
   var ArrayProto = Array.prototype, ObjProto = Object.prototype;
 
   // Create quick reference variables for speed access to core prototypes.
-  var slice                 = ArrayProto.slice,
-      unshift               = ArrayProto.unshift,
-      toString              = ObjProto.toString,
-      hasOwnProperty        = ObjProto.hasOwnProperty,
-      propertyIsEnumerable  = ObjProto.propertyIsEnumerable;
+  var slice            = ArrayProto.slice,
+      unshift          = ArrayProto.unshift,
+      toString         = ObjProto.toString,
+      hasOwnProperty   = ObjProto.hasOwnProperty;
 
   // All **ECMAScript 5** native function implementations that we hope to use
   // are declared here.