diff --git a/misc/ajax.js b/misc/ajax.js
index ade1f70294975491ad7750b1222638f5322c2529..73848602fe57840d008497543d8215df33a5f4f1 100644
--- a/misc/ajax.js
+++ b/misc/ajax.js
@@ -280,7 +280,7 @@ Drupal.ajax.prototype.success = function (response, status) {
   if (this.progress.object) {
     this.progress.object.stopMonitoring();
   }
-  $(this.element).removeClass('progress-disabled').attr('disabled', false);
+  $(this.element).removeClass('progress-disabled').removeAttr('disabled');
 
   Drupal.freezeHeight();
 
@@ -348,7 +348,7 @@ Drupal.ajax.prototype.error = function (response, uri) {
   // Undo hide.
   $(this.wrapper).show();
   // Re-enable the element.
-  $(this.element).removeClass('progress-disabled').attr('disabled', false);
+  $(this.element).removeClass('progress-disabled').removeAttr('disabled');
   // Reattach behaviors, if they were detached in beforeSerialize().
   if (this.form) {
     var settings = response.settings || this.settings || Drupal.settings;