diff --git a/components/script/dom/webidls/HTMLFormElement.webidl b/components/script/dom/webidls/HTMLFormElement.webidl
index e9607b6170e..e2423dcce6c 100644
--- a/components/script/dom/webidls/HTMLFormElement.webidl
+++ b/components/script/dom/webidls/HTMLFormElement.webidl
@@ -16,7 +16,7 @@ interface HTMLFormElement : HTMLElement {
            attribute boolean noValidate;
            attribute DOMString target;
 
-  //readonly attribute HTMLFormControlsCollection elements;
+  //[SameObject] readonly attribute HTMLFormControlsCollection elements;
   //readonly attribute long length;
   //getter Element (unsigned long index);
   //getter (RadioNodeList or Element) (DOMString name);