diff --git a/src/tray-menu.hpp b/src/tray-menu.hpp
index 952260a..9e78abc 100644
--- a/src/tray-menu.hpp
+++ b/src/tray-menu.hpp
@@ -30,6 +30,8 @@
 
 #include <QtQml/QQmlContext>
 
+#include "key-viewer-dialog.hpp"
+
 namespace ndn {
 
 class TrayMenu : public QWidget
@@ -90,6 +92,8 @@
   QAction* m_entryPref;
   QAction* m_entrySec;
   QAction* m_entryQuit;
+
+  ncc::KeyViewerDialog* m_keyViewerDialog;
 };
 
 } // namespace ndn