diff --git a/mozilla/widget/src/mac/nsMacWindow.cpp b/mozilla/widget/src/mac/nsMacWindow.cpp
index 9fb273107d7..6c80c3a561f 100644
--- a/mozilla/widget/src/mac/nsMacWindow.cpp
+++ b/mozilla/widget/src/mac/nsMacWindow.cpp
@@ -915,9 +915,11 @@ NS_IMETHODIMP nsMacWindow::Show(PRBool bState)
     }
     else
 #endif
-    ::HideWindow(mWindowPtr);
+    if ( mWindowPtr ) {
+      ::HideWindow(mWindowPtr);
     }
-    return NS_OK;
+  }
+  return NS_OK;
 }