diff --git a/install-usercss.html b/install-usercss.html
index ae6ea04e..ca301b1d 100644
--- a/install-usercss.html
+++ b/install-usercss.html
@@ -10,6 +10,7 @@
   <script src="/js/prefs.js"></script>
   <script src="/js/dom.js"></script>
   <script src="/js/localization.js"></script>
+  <script src="/content/apply.js"></script>
   <script src="/vendor/node-semver/semver.js"></script>
 
   <script src="/msgbox/msgbox.js"></script>