diff --git a/src/core.js b/src/core.js
index 87d5555be..89bbde5c0 100644
--- a/src/core.js
+++ b/src/core.js
@@ -358,9 +358,11 @@ jQuery.extend = jQuery.fn.extend = function() {
 
 jQuery.extend({
 	noConflict: function( deep ) {
-		window.$ = _$;
+		if ( window.$ === jQuery ) {
+			window.$ = _$;
+		}
 
-		if ( deep ) {
+		if ( deep && window.jQuery === jQuery ) {
 			window.jQuery = _jQuery;
 		}