diff --git a/js/filter.admin.js b/js/filter.admin.js
index 610060c..e514567 100644
--- a/js/filter.admin.js
+++ b/js/filter.admin.js
@@ -1,12 +1,12 @@
 (function ($) {
-
+  'use strict';
   Drupal.behaviors.commonMarkFilterStatus = {
     attach: function (context, settings) {
       var $document = $(document);
 
       // Duplicate the "click" event from filter module's filter.admin.js but
       // for the "checked" States API event.
-      $document.bind('state:checked', function(e) {
+      $document.bind('state:checked', function (e) {
         if (e.target) {
           var $checkbox = $(e.target);