diff --git a/content/install-user-css.js b/content/install-user-css.js
index 4dc073ed..8897d916 100644
--- a/content/install-user-css.js
+++ b/content/install-user-css.js
@@ -8,7 +8,7 @@ function install(style) {
   const request = Object.assign(style, {
     method: 'saveUsercss',
     reason: 'update',
-    updateUrl: location.href
+    updateUrl: location.protocol === 'file:' ? null : location.href
   });
   return runtimeSend(request)
     .then(result => {