diff --git a/include/lib/libc/stdlib.h b/include/lib/libc/stdlib.h
index 84ba37f..24e7bae 100644
--- a/include/lib/libc/stdlib.h
+++ b/include/lib/libc/stdlib.h
@@ -11,15 +11,11 @@
 #ifndef STDLIB_H
 #define STDLIB_H
 
-#include <stdlib_.h>
+#include <stddef.h>
 
 #define EXIT_FAILURE 1
 #define EXIT_SUCCESS 0
 
-#ifndef NULL
-#define NULL ((void *) 0)
-#endif
-
 #define _ATEXIT_MAX 1
 
 extern void abort(void);