diff --git a/include/stddef.h b/include/stddef.h
index 3230a32b0..ca93edf62 100644
--- a/include/stddef.h
+++ b/include/stddef.h
@@ -54,7 +54,7 @@ typedef unsigned size_t;
 
 /* NULL pointer */
 #ifndef _HAVE_NULL
-#define NULL    0
+#define NULL    ((void *) 0)
 #define _HAVE_NULL
 #endif