diff --git a/mozilla/accessible/src/base/nsAccessNode.cpp b/mozilla/accessible/src/base/nsAccessNode.cpp
index 6897b077648..b748518b4a8 100755
--- a/mozilla/accessible/src/base/nsAccessNode.cpp
+++ b/mozilla/accessible/src/base/nsAccessNode.cpp
@@ -225,8 +225,10 @@ NS_IMETHODIMP nsAccessNode::GetUniqueID(void **aUniqueID)
 
 NS_IMETHODIMP nsAccessNode::GetOwnerWindow(void **aWindow)
 {
+  *aWindow = nsnull;
   nsCOMPtr<nsIAccessibleDocument> docAccessible(GetDocAccessible());
-  NS_ASSERTION(docAccessible, "No root accessible pointer back, Init() not called.");
+  if (!docAccessible)
+    return NS_ERROR_FAILURE; // This node or doc accessible is shut down
   return docAccessible->GetWindowHandle(aWindow);
 }
 
diff --git a/mozilla/accessible/src/msaa/nsAccessibleWrap.cpp b/mozilla/accessible/src/msaa/nsAccessibleWrap.cpp
index 9835e335e09..ee3adfbb40d 100644
--- a/mozilla/accessible/src/msaa/nsAccessibleWrap.cpp
+++ b/mozilla/accessible/src/msaa/nsAccessibleWrap.cpp
@@ -1394,6 +1394,9 @@ STDMETHODIMP
 nsAccessibleWrap::get_windowHandle(HWND *windowHandle)
 {
 __try {
+  *windowHandle = 0;
+  if (!mDOMNode)
+    return E_FAIL;
   void *handle = nsnull;
   nsresult rv = GetOwnerWindow(&handle);
   if (NS_FAILED(rv))