diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index eb39fc9..984ceb3 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -167,7 +167,8 @@
 extern int	wctomb(char *, wchar_t);
 extern size_t	wcstombs(char *, const wchar_t *, size_t);
 
-#define MB_CUR_MAX 4U
+extern size_t __mb_cur_max(void);
+#define MB_CUR_MAX __mb_cur_max()
 
 __END_DECLS