diff --git a/content/html/content/src/nsHTMLButtonElement.cpp b/content/html/content/src/nsHTMLButtonElement.cpp
index a8f45230ad0a..0b0cf405322b 100644
--- a/content/html/content/src/nsHTMLButtonElement.cpp
+++ b/content/html/content/src/nsHTMLButtonElement.cpp
@@ -434,7 +434,9 @@ nsHTMLButtonElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
                          nsMouseEvent::eRightButton) {
               // cancel all of these events for buttons
               //XXXsmaug What to do with these events? Why these should be cancelled?
-              aVisitor.mDOMEvent->StopPropagation();
+              if (aVisitor.mDOMEvent) {
+                aVisitor.mDOMEvent->StopPropagation();
+              }
             }
           }
         }