diff --git a/mozilla/widget/src/xpwidgets/nsBaseDragService.cpp b/mozilla/widget/src/xpwidgets/nsBaseDragService.cpp
index 01f250a42ff..cf4950c0bd7 100644
--- a/mozilla/widget/src/xpwidgets/nsBaseDragService.cpp
+++ b/mozilla/widget/src/xpwidgets/nsBaseDragService.cpp
@@ -363,6 +363,9 @@ static nsIPresShell*
 GetPresShellForContent(nsIDOMNode* aDOMNode)
 {
   nsCOMPtr<nsIContent> content = do_QueryInterface(aDOMNode);
+  if (!content)
+    return nsnull;
+
   nsCOMPtr<nsIDocument> document = content->GetCurrentDoc();
   if (document) {
     document->FlushPendingNotifications(Flush_Display);