diff --git a/underscore.js b/underscore.js
index ed09b2f68..41cd7ce2a 100644
--- a/underscore.js
+++ b/underscore.js
@@ -387,8 +387,7 @@
       return array[i] === item ? i : -1;
     }
     if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);
-    var o,i=0;
-    while( o = array[i++] ) if (o === item) return i-1;
+    for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;
     return -1;
   };