diff --git a/accessible/src/base/nsAccessibilityService.cpp b/accessible/src/base/nsAccessibilityService.cpp
index 6827529f6f6..d5f6d86c482 100644
--- a/accessible/src/base/nsAccessibilityService.cpp
+++ b/accessible/src/base/nsAccessibilityService.cpp
@@ -635,6 +635,9 @@ nsAccessibilityService::GetAccessibleFor(nsIDOMNode *aNode,
                                          nsIAccessible **aAccessible)
 {
   NS_ENSURE_ARG_POINTER(aAccessible);
+  *aAccessible = nsnull;
+  if (!aNode)
+    return NS_OK;
 
   nsCOMPtr<nsINode> node(do_QueryInterface(aNode));
   NS_IF_ADDREF(*aAccessible = GetAccessible(node));