diff --git a/dom/webidl/Window.webidl b/dom/webidl/Window.webidl
index 22b0539cf..deee3842f 100644
--- a/dom/webidl/Window.webidl
+++ b/dom/webidl/Window.webidl
@@ -499,7 +499,7 @@ partial interface Window {
   [Throws, Pref="tenfourfox.dom.requestIdleCallback.enabled"]
   unsigned long requestIdleCallback(IdleRequestCallback callback,
                                     optional IdleRequestOptions options);
-  [Pref="dom.requestIdleCallback.enabled"]
+  [Pref="tenfourfox.dom.requestIdleCallback.enabled"]
   void          cancelIdleCallback(unsigned long handle);
 };