diff --git a/dom.bs b/dom.bs
index 004482c8e..340e4101c 100644
--- a/dom.bs
+++ b/dom.bs
@@ -4715,7 +4715,8 @@ object may be returned as returned by an earlier call.
 
 <pre class=idl force="Document">
 [Constructor,
- Exposed=Window]
+ Exposed=Window,
+ LegacyWindowAlias=HTMLDocument]
 interface Document : Node {
   [SameObject] readonly attribute DOMImplementation implementation;
   readonly attribute USVString URL;