diff --git a/interfaces/css-regions.idl b/interfaces/css-regions.idl
index 1e2396007d0d61..254ef53b69b1ea 100644
--- a/interfaces/css-regions.idl
+++ b/interfaces/css-regions.idl
@@ -25,11 +25,9 @@ interface NamedFlow : EventTarget {
   sequence<Region> getRegionsByContent(Node node);
 };
 
-[Exposed=Window,
- NoInterfaceObject]
 interface Region {
   readonly attribute CSSOMString regionOverset;
   sequence<Range>? getRegionFlowRanges();
 };
 
-Element implements Region;
+Element includes Region;