diff --git a/js/jquery.mobile.js b/js/jquery.mobile.js
index 365c7d10..8ff11b76 100644
--- a/js/jquery.mobile.js
+++ b/js/jquery.mobile.js
@@ -47,7 +47,7 @@
 		metaViewportContent: "width=device-width, minimum-scale=1, maximum-scale=1",
 		
 		//additional markup to prepend to head
-		headExtras: undefined,
+		headExtras: null,
 		
 		//support conditions that must be met in order to proceed
 		gradeA: function(){