diff --git a/reactos/include/reactos/winlogon.h b/reactos/include/reactos/winlogon.h
index 4c00b674e81..42eaf620468 100644
--- a/reactos/include/reactos/winlogon.h
+++ b/reactos/include/reactos/winlogon.h
@@ -17,6 +17,14 @@
 #define EWX_INTERNAL_KILL_ALL_APPS  (EWX_INTERNAL_FLAG | 0x200)
 #define EWX_INTERNAL_FLAG_LOGOFF    0x1000
 
+#define WM_LOGONNOTIFY 0x0000004c
+
+/* WPARAM values for WM_LOGONNOTIFY */
+#define LN_START_TASK_MANAGER 0x4
+#define LN_LOCK_WORKSTATION   0x5
+#define LN_UNLOCK_WORKSTATION 0x6
+#define LN_MESSAGE_BEEP       0x9
+
 #endif /* REACTOS_WINLOGON_H_INCLUDED */
 
 /* EOF */