diff --git a/content/html/content/src/nsGenericHTMLElement.h b/content/html/content/src/nsGenericHTMLElement.h
index 20827b70f87..5347bb0d125 100644
--- a/content/html/content/src/nsGenericHTMLElement.h
+++ b/content/html/content/src/nsGenericHTMLElement.h
@@ -37,7 +37,6 @@ class nsHTMLFormElement;
 class nsIDOMHTMLMenuElement;
 class nsIDOMHTMLCollection;
 class nsDOMSettableTokenList;
-class nsIDOMDOMStringMap;
 
 namespace mozilla {
 namespace dom{