diff --git a/content/html/content/src/nsHTMLFormElement.cpp b/content/html/content/src/nsHTMLFormElement.cpp
index 73115cc76aa..c3febeec7fc 100644
--- a/content/html/content/src/nsHTMLFormElement.cpp
+++ b/content/html/content/src/nsHTMLFormElement.cpp
@@ -2246,7 +2246,8 @@ nsFormControlList::AddElementToTable(nsIFormControl* aChild,
       // Add the new child too
       list->AppendElement(newChild);
 
-      nsCOMPtr<nsISupports> listSupports = do_QueryInterface(list);
+      nsCOMPtr<nsISupports> listSupports =
+        do_QueryInterface(static_cast<nsIDOMNodeList>(list));
 
       // Replace the element with the list.
       NS_ENSURE_TRUE(mNameLookupTable.Put(aName, listSupports),