diff --git a/src/core.js b/src/core.js
index a6d4c5f74..b9a2fed49 100644
--- a/src/core.js
+++ b/src/core.js
@@ -24,7 +24,10 @@ var jQuery = window.jQuery = window.$ = function( selector, context ) {
 var quickExpr = /^[^<]*(<(.|\s)+>)[^>]*$|^#(\w+)$/,
 
 // Is it a simple selector
-	isSimple = /^.[^:#\[\.]*$/;
+	isSimple = /^.[^:#\[\.]*$/,
+
+// Will speed up references to undefined, and allows munging its name.	
+	undefined;
 
 jQuery.fn = jQuery.prototype = {
 	init: function( selector, context ) {