diff --git a/fullscreen.bs b/fullscreen.bs
index 9b53890..efe1364 100644
--- a/fullscreen.bs
+++ b/fullscreen.bs
@@ -144,7 +144,7 @@ partial interface Element {
 
 partial interface Document {
   [LenientSetter] readonly attribute boolean fullscreenEnabled;
-  [LenientSetter] readonly attribute boolean fullscreen; // historical
+  [LenientSetter, Unscopable] readonly attribute boolean fullscreen; // historical
 
   Promise<void> exitFullscreen();