diff --git a/mozilla/dom/src/base/nsGlobalWindow.cpp b/mozilla/dom/src/base/nsGlobalWindow.cpp
index 7cdc866a48d..37f4debd323 100644
--- a/mozilla/dom/src/base/nsGlobalWindow.cpp
+++ b/mozilla/dom/src/base/nsGlobalWindow.cpp
@@ -290,7 +290,7 @@ NS_IMETHODIMP
 GlobalWindowImpl::GetDocument(nsIDOMDocument** aDocument)
 {
   *aDocument = mDocument;
-  NS_ADDREF(mDocument);
+  NS_IF_ADDREF(mDocument);
 
   return NS_OK;
 }