--- a/toolkit/components/passwordmgr/nsLoginManager.js
+++ b/toolkit/components/passwordmgr/nsLoginManager.js
@@ -279,16 +279,17 @@ LoginManager.prototype = {
         handleEvent : function (event) {
             if (!event.isTrusted)
                 return;
 
             this._pwmgr.log("domEventListener: got event " + event.type);
 
             switch (event.type) {
                 case "DOMContentLoaded":
+                    event.target.removeEventListener(event.type, this, false);
                     this._pwmgr._fillDocument(event.target);
                     return;
 
                 case "DOMAutoComplete":
                 case "blur":
                     var acInputField = event.target;
                     var acForm = acInputField.form;