diff --git a/content/base/src/nsDocument.cpp b/content/base/src/nsDocument.cpp
index 96184a0899aa..7559bd8cd5c9 100644
--- a/content/base/src/nsDocument.cpp
+++ b/content/base/src/nsDocument.cpp
@@ -4543,7 +4543,7 @@ nsDocument::GetListenerManager(PRBool aCreateIfNotFound,
   return NS_OK;
 }
 
-NS_IMETHODIMP
+nsresult
 nsDocument::GetSystemEventGroup(nsIDOMEventGroup **aGroup)
 {
   nsCOMPtr<nsIEventListenerManager> manager;