diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 75d3c1861a..3ef2f6cd8c 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -3545,7 +3545,9 @@ nsGlobalWindow::GetEventTargetParent(EventChainPreVisitor& aVisitor)
 
   aVisitor.mCanHandle = true;
   // Middle/right click shouldn't dispatch click event, use auxclick to instead.
-  if (mDoc->IsXULDocument()) {
+  // Note: mDoc should always exist here, but check just in case someone yanked
+  // it out from under us.
+  if (mDoc && mDoc->IsXULDocument()) {
     aVisitor.mForceContentDispatch = true; //FIXME! Bug 329119
   }
   if (msg == eResize && aVisitor.mEvent->IsTrusted()) {