diff --git a/widget/gtk2/nsColorPicker.h b/widget/gtk2/nsColorPicker.h
index cb50910c1c4..1f3bd258e6a 100644
--- a/widget/gtk2/nsColorPicker.h
+++ b/widget/gtk2/nsColorPicker.h
@@ -14,7 +14,7 @@
 
 class nsIWidget;
 
-class nsColorPicker : public nsIColorPicker
+class nsColorPicker MOZ_FINAL : public nsIColorPicker
 {
 public:
   NS_DECL_ISUPPORTS