diff --git a/include/reactos/undocuser.h b/include/reactos/undocuser.h
index f5cfa763305..973d435b2a9 100644
--- a/include/reactos/undocuser.h
+++ b/include/reactos/undocuser.h
@@ -32,6 +32,7 @@
 #define WM_COPYGLOBALDATA   0x00000049
 #define WM_LOGONNOTIFY      0x0000004C
 #define WM_KEYF1            0x0000004D
+#define WM_KLUDGEMINRECT    0x0000008B
 #define WM_NCUAHDRAWCAPTION 0x000000AE
 #define WM_NCUAHDRAWFRAME   0x000000AF
 #define WM_SYSTIMER         0x00000118