diff --git a/dom/webidl/LegacyQueryInterface.webidl b/dom/webidl/LegacyQueryInterface.webidl
index 24a44fa53735..0ebe513ae7fc 100644
--- a/dom/webidl/LegacyQueryInterface.webidl
+++ b/dom/webidl/LegacyQueryInterface.webidl
@@ -17,4 +17,3 @@ interface LegacyQueryInterface {
 };
 
 Element implements LegacyQueryInterface;
-Window implements LegacyQueryInterface;