--- a/cuffs-hulotte-popup.user.js	Thu Jul 20 09:11:13 2017 +0000
+++ b/cuffs-hulotte-popup.user.js	Thu Jul 20 20:29:43 2017 +0900
@@ -1,7 +1,7 @@
 // ==UserScript==
 // @name         Cuffs/Hulotte popup disable
 // @namespace    https://myconan.net
-// @version      1.0.3
+// @version      1.0.4
 // @description  Strip out Cuffs/Hulotte age confirmation popup
 // @author       nanaya
 // @match        http://www.cuffs.co.jp/*
@@ -13,6 +13,10 @@
 ;(function() {
   "use strict";
 
+  if (document.querySelector('body > #mainContent') == null) {
+    return;
+  }
+
   var styleEl = document.createElement('style');
   document.head.appendChild(styleEl);
   var styleSheet = styleEl.sheet;
@@ -21,4 +25,4 @@
     'body > :not(#mainContent) { display: none !important; }',
     styleSheet.cssRules.length
   );
-}).call();
\ No newline at end of file
+}).call();