diff --git a/src/include/dirent.h b/src/include/dirent.h
index cb0cab98..61a5e011 100644
--- a/src/include/dirent.h
+++ b/src/include/dirent.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dirent.h,v 1.33 2013/12/13 18:09:27 zhuk Exp $	*/
+/*	$OpenBSD: dirent.h,v 1.34 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: dirent.h,v 1.9 1995/03/26 20:13:37 jtc Exp $	*/
 
 /*-
@@ -63,15 +63,7 @@ typedef struct _dirdesc DIR;
 /* definitions for library routines operating on directories. */
 #define	DIRBLKSIZ	1024
 
-#ifndef NULL
-#ifdef 	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif /* __GNUG__ */
-#endif /* !NULL */
+#include <sys/_null.h>
 
 #endif /* __BSD_VISIBLE */
 
diff --git a/src/include/locale.h b/src/include/locale.h
index 3ce65c56..38d7a408 100644
--- a/src/include/locale.h
+++ b/src/include/locale.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locale.h,v 1.9 2014/07/14 07:22:07 pelikan Exp $	*/
+/*	$OpenBSD: locale.h,v 1.10 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: locale.h,v 1.6 1994/10/26 00:56:02 cgd Exp $	*/
 
 /*
@@ -35,6 +35,8 @@
 #ifndef _LOCALE_H_
 #define _LOCALE_H_
 
+#include <sys/_null.h>
+
 struct lconv {
 	char	*decimal_point;
 	char	*thousands_sep;
@@ -62,16 +64,6 @@ struct lconv {
 	char	int_n_sign_posn;
 };
 
-#ifndef NULL
-#ifdef 	__GNUG__
-#define NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #define	LC_ALL		0
 #define	LC_COLLATE	1
 #define	LC_CTYPE	2
diff --git a/src/include/stddef.h b/src/include/stddef.h
index 52b2b39d..88bd55f1 100644
--- a/src/include/stddef.h
+++ b/src/include/stddef.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: stddef.h,v 1.12 2011/07/03 18:51:01 jsg Exp $	*/
+/*	$OpenBSD: stddef.h,v 1.13 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: stddef.h,v 1.4 1994/10/26 00:56:26 cgd Exp $	*/
 
 /*-
@@ -36,6 +36,7 @@
 #define _STDDEF_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <sys/_types.h>
 
 #ifndef _PTRDIFF_T_DEFINED_
@@ -64,16 +65,6 @@ typedef	__wint_t	wint_t;
 typedef	__mbstate_t	mbstate_t;
 #endif
 
-#ifndef	NULL
-#ifdef 	__GNUG__
-#define NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #if __GNUC_PREREQ__(4, 0)
 #define	offsetof(type, member)	__builtin_offsetof(type, member)
 #else
diff --git a/src/include/stdio.h b/src/include/stdio.h
index c22d5f70..3f39a213 100644
--- a/src/include/stdio.h
+++ b/src/include/stdio.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: stdio.h,v 1.52 2016/03/16 04:56:08 deraadt Exp $	*/
+/*	$OpenBSD: stdio.h,v 1.53 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: stdio.h,v 1.18 1996/04/25 18:29:21 jtc Exp $	*/
 
 /*-
@@ -39,6 +39,7 @@
 #define	_STDIO_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <sys/_types.h>
 
 #if __BSD_VISIBLE || __POSIX_VISIBLE || __XPG_VISIBLE
@@ -55,16 +56,6 @@ typedef	__size_t	size_t;
 typedef	__off_t	off_t;
 #endif
 
-#ifndef NULL
-#ifdef 	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #define	_FSTDIO			/* Define for new stdio with functions. */
 
 typedef off_t fpos_t;		/* stdio file position type */
diff --git a/src/include/stdlib.h b/src/include/stdlib.h
index ba4f32c9..09f50ece 100644
--- a/src/include/stdlib.h
+++ b/src/include/stdlib.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: stdlib.h,v 1.65 2015/07/14 19:05:11 millert Exp $	*/
+/*	$OpenBSD: stdlib.h,v 1.66 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: stdlib.h,v 1.25 1995/12/27 21:19:08 jtc Exp $	*/
 
 /*-
@@ -36,6 +36,7 @@
 #define _STDLIB_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <machine/_types.h>
 #if __BSD_VISIBLE	/* for quad_t, etc. (XXX - use protected types) */
 #include <sys/types.h>
@@ -76,17 +77,6 @@ typedef struct {
 } qdiv_t;
 #endif
 
-
-#ifndef	NULL
-#ifdef 	__GNUG__
-#define NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #define	EXIT_FAILURE	1
 #define	EXIT_SUCCESS	0
 
diff --git a/src/include/string.h b/src/include/string.h
index 41222081..b4c880ce 100644
--- a/src/include/string.h
+++ b/src/include/string.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: string.h,v 1.30 2015/11/20 23:40:32 millert Exp $	*/
+/*	$OpenBSD: string.h,v 1.31 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: string.h,v 1.6 1994/10/26 00:56:30 cgd Exp $	*/
 
 /*-
@@ -36,6 +36,7 @@
 #define	_STRING_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <machine/_types.h>
 
 /*
@@ -51,16 +52,6 @@
 typedef	__size_t	size_t;
 #endif
 
-#ifndef	NULL
-#ifdef 	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 __BEGIN_DECLS
 void	*memchr(const void *, int, size_t);
 int	 memcmp(const void *, const void *, size_t);
diff --git a/src/include/time.h b/src/include/time.h
index 8c432b06..a73f9c3a 100644
--- a/src/include/time.h
+++ b/src/include/time.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: time.h,v 1.28 2015/04/07 01:47:04 millert Exp $	*/
+/*	$OpenBSD: time.h,v 1.29 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: time.h,v 1.9 1994/10/26 00:56:35 cgd Exp $	*/
 
 /*
@@ -42,18 +42,9 @@
 #define	_TIME_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <sys/_types.h>
 
-#ifndef	NULL
-#ifdef 	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #ifndef	_CLOCK_T_DEFINED_
 #define	_CLOCK_T_DEFINED_
 typedef	__clock_t	clock_t;
diff --git a/src/include/unistd.h b/src/include/unistd.h
index 3cfe9a6e..9724e275 100644
--- a/src/include/unistd.h
+++ b/src/include/unistd.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: unistd.h,v 1.101 2016/05/23 00:12:58 guenther Exp $ */
+/*	$OpenBSD: unistd.h,v 1.102 2016/09/09 18:12:37 millert Exp $ */
 /*	$NetBSD: unistd.h,v 1.26.4.1 1996/05/28 02:31:51 mrg Exp $	*/
 
 /*-
@@ -35,6 +35,7 @@
 #ifndef _UNISTD_H_
 #define	_UNISTD_H_
 
+#include <sys/_null.h>
 #include <sys/types.h>
 #include <sys/unistd.h>
 
@@ -314,17 +315,6 @@
 #define	_CS_POSIX_V7_WIDTH_RESTRICTED_ENVS	30
 #define	_CS_V7_ENV				31
 
-
-#ifndef NULL
-#ifdef 	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #ifndef	_INTPTR_T_DEFINED_
 #define	_INTPTR_T_DEFINED_
 typedef	__intptr_t		intptr_t;
diff --git a/src/include/wchar.h b/src/include/wchar.h
index 270bd6c6..7cdee59a 100644
--- a/src/include/wchar.h
+++ b/src/include/wchar.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: wchar.h,v 1.29 2015/04/04 18:05:05 guenther Exp $	*/
+/*	$OpenBSD: wchar.h,v 1.30 2016/09/09 18:12:37 millert Exp $	*/
 /*	$NetBSD: wchar.h,v 1.16 2003/03/07 07:11:35 tshiozak Exp $	*/
 
 /*-
@@ -60,18 +60,9 @@
 #define _WCHAR_H_
 
 #include <sys/cdefs.h>
+#include <sys/_null.h>
 #include <sys/_types.h>
 
-#ifndef	NULL
-#ifdef	__GNUG__
-#define	NULL	__null
-#elif defined(__cplusplus)
-#define	NULL	0L
-#else
-#define	NULL	((void *)0)
-#endif
-#endif
-
 #include <stdio.h> /* for FILE* */
 
 #if !defined(_WCHAR_T_DEFINED_) && !defined(__cplusplus)