diff --git a/src/ajax/script.js b/src/ajax/script.js
index 48b329ae3..ada74ff67 100644
--- a/src/ajax/script.js
+++ b/src/ajax/script.js
@@ -40,7 +40,7 @@ jQuery.ajaxTransport( "script", function(s) {
 
 				script = document.createElement( "script" );
 
-				script.async = "async";
+				script.async = true;
 
 				if ( s.scriptCharset ) {
 					script.charset = s.scriptCharset;