diff --git a/source b/source
index e0735c43270..5047ab695c0 100644
--- a/source
+++ b/source
@@ -86853,7 +86853,7 @@ interface <dfn interface>Window</dfn> : <span>EventTarget</span> {
 
   // the user agent
   readonly attribute <span>Navigator</span> <span data-x="dom-navigator">navigator</span>;
-  readonly attribute <span>Navigator</span> <span data-x="dom-clientInformation">clientInformation</span>; // legacy alias of .navigator
+  [Replaceable] readonly attribute <span>Navigator</span> <span data-x="dom-clientInformation">clientInformation</span>; // legacy alias of .navigator
   readonly attribute boolean <span data-x="dom-originAgentCluster">originAgentCluster</span>;
 
   // user prompts