diff --git a/misc/ajax.js b/misc/ajax.js
index 01b894d..81cb20b 100644
--- a/misc/ajax.js
+++ b/misc/ajax.js
@@ -372,7 +372,7 @@ Drupal.ajax.prototype.beforeSend = function (xmlhttprequest, options) {
     $(this.element).after(this.progress.element);
   }
   else if (this.progress.type == 'throbber') {
-    this.progress.element = $('<div class="ajax-progress ajax-progress-throbber"><div class="throbber">&nbsp;</div></div>');
+    this.progress.element = $(Drupal.theme('throbber'));
     if (this.progress.message) {
       $('.throbber', this.progress.element).after('<div class="message">' + this.progress.message + '</div>');
     }
@@ -647,3 +647,13 @@ Drupal.ajax.prototype.commands = {
 };
 
 })(jQuery);
+
+/**
+ * Theme function for a throbber element.
+ *
+ * @return
+ *   This function has to return HTML markup for the element.
+ */
+Drupal.theme.prototype.throbber = function() {
+  return '<div class="ajax-progress ajax-progress-throbber"><div class="throbber">&nbsp;</div></div>';
+}