diff --git a/editor/libeditor/base/nsEditorEventListener.cpp b/editor/libeditor/base/nsEditorEventListener.cpp
index 9a4eb2c75b2..5344958416a 100644
--- a/editor/libeditor/base/nsEditorEventListener.cpp
+++ b/editor/libeditor/base/nsEditorEventListener.cpp
@@ -713,7 +713,8 @@ nsEditorEventListener::CanDrop(nsIDOMDragEvent* aEvent)
   // is the same as the drag source.
   nsCOMPtr<nsIDOMNode> sourceNode;
   dataTransferNS->GetMozSourceNode(getter_AddRefs(sourceNode));
-  NS_ENSURE_TRUE(sourceNode, PR_TRUE);
+  if (!sourceNode)
+    return PR_TRUE;
 
   // There is a source node, so compare the source documents and this document.
   // Disallow drops on the same document.