diff --git a/include/winnt.h b/include/winnt.h
index 73a2ae84e9a..0be60405987 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -1970,6 +1970,10 @@ NTSYSAPI void WINAPI RtlCaptureContext(CONTEXT*);
 #define LOCALE_USER_DEFAULT	(MAKELCID(LANG_USER_DEFAULT, SORT_DEFAULT))
 #define LOCALE_NEUTRAL		(MAKELCID(MAKELANGID(LANG_NEUTRAL,SUBLANG_NEUTRAL),SORT_DEFAULT))
 #define LOCALE_INVARIANT	(MAKELCID(MAKELANGID(LANG_INVARIANT,SUBLANG_NEUTRAL),SORT_DEFAULT))
+#define LOCALE_CUSTOM_DEFAULT      (MAKELCID(MAKELANGID(LANG_NEUTRAL,SUBLANG_CUSTOM_DEFAULT),SORT_DEFAULT))
+#define LOCALE_CUSTOM_UNSPECIFIED  (MAKELCID(MAKELANGID(LANG_NEUTRAL,SUBLANG_CUSTOM_UNSPECIFIED),SORT_DEFAULT))
+#define LOCALE_CUSTOM_UI_DEFAULT   (MAKELCID(MAKELANGID(LANG_NEUTRAL,SUBLANG_UI_CUSTOM_DEFAULT),SORT_DEFAULT))
+
 
 #define UNREFERENCED_PARAMETER(u)	(void)(u)
 #define DBG_UNREFERENCED_PARAMETER(u)	(void)(u)