diff --git a/core/misc/drupal.js b/core/misc/drupal.js
index da5e1c1734498cb3089ade920de95a22f9855732..6ea7b45cfc028615ebda98c931e1a5173501c4ec 100644
--- a/core/misc/drupal.js
+++ b/core/misc/drupal.js
@@ -369,7 +369,4 @@ Drupal.theme.placeholder = function (str) {
   return '<em class="placeholder">' + Drupal.checkPlain(str) + '</em>';
 };
 
-Drupal.AjaxError.prototype = new Error();
-Drupal.AjaxError.prototype.constructor = Drupal.AjaxError;
-
 })(domready, Drupal, window.drupalSettings);