diff --git a/browser/base/content/browser-init.js b/browser/base/content/browser-init.js
index a79a9734619f89639c15087fe28e9615354a7209..edaef604d33d76b570571e1bbb2ebc590e045d87 100644
--- a/browser/base/content/browser-init.js
+++ b/browser/base/content/browser-init.js
@@ -237,6 +237,9 @@ var gBrowserInit = {
     gPrivateBrowsingUI.init();
     BrowserSearch.init();
     BrowserPageActions.init();
+
+    Services.scriptloader.loadSubScript("chrome://browser/content/zenThemeModifier.js", window);
+
     if (gToolbarKeyNavEnabled) {
       ToolbarKeyboardNavigator.init();
     }