diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 0613872..5c7545a 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -437,7 +437,7 @@
       ajax.options.url += queryParameter;
     }
     else {
-      var regexPattern = new RegExp(Drupal.ajax.WRAPPER_FORMAT + '=\\w*');
+      var regexPattern = new RegExp(Drupal.ajax.WRAPPER_FORMAT + '=[^&]*', 'i');
       ajax.options.url = ajax.options.url.replace(regexPattern, queryParameter);
     }