diff --git a/libc/include/locale.h b/libc/include/locale.h
index a8f03bc..a681a17 100644
--- a/libc/include/locale.h
+++ b/libc/include/locale.h
@@ -32,6 +32,9 @@
 #include <sys/cdefs.h>
 #include <xlocale.h>
 
+#define __need_NULL
+#include <stddef.h>
+
 __BEGIN_DECLS
 
 #define LC_CTYPE           0