diff --git a/inc/stdlib.h b/inc/stdlib.h
index d702748..3372ab4 100644
--- a/inc/stdlib.h
+++ b/inc/stdlib.h
@@ -1,15 +1,19 @@
 #pragma once
-// Defines NULL
-#include <stddef.h>
 
 #if !defined(__STDC_LIB_EXT1__)
-#define __STDC_LIB_EXT1__
+    #define __STDC_LIB_EXT1__
 #endif
 
 #ifdef __STDC_WANT_SECURE_LIB__
-#if !defined(__STDC_WANT_LIB_EXT1__)
-#define __STDC_WANT_LIB_EXT1__ 1
+    #if !defined(__STDC_WANT_LIB_EXT1__)
+        #define __STDC_WANT_LIB_EXT1__ 1
+    #endif
 #endif
+
+#include <types/size.h>
+
+#if !defined(NULL)
+    #define NULL ((void *)0)
 #endif
 
 #define EXIT_SUCCESS 0
diff --git a/inc/types/size.c b/inc/types/size.h
similarity index 100%
rename from inc/types/size.c
rename to inc/types/size.h