--- a/uriloader/exthandler/nsExternalProtocolHandler.cpp
+++ b/uriloader/exthandler/nsExternalProtocolHandler.cpp
@@ -320,16 +320,18 @@ NS_IMETHODIMP nsExtProtocolChannel::Asyn
   if (NS_SUCCEEDED(rv)) {
 
     // redirecting to the web handler involvegs calling OnChannelRedirect,
     // which is supposed to happen after AsyncOpen completes, so we do it in an
     // event
     nsCOMPtr<nsIRunnable> event = new nsWebProtocolRedirect(mUrl, uriTemplate,
                                                             listener, ctxt, 
                                                             this);
+    // We don't check if |event| was successfully created because
+    // |NS_DispatchToCurrentThread| will do that for us.
     rv = NS_DispatchToCurrentThread(event);
     if (NS_SUCCEEDED(rv)) {
       return rv;
     }
   }
 
   // try for an OS-provided handler
   OpenURL();