diff --git a/sys/kern/sysv_ipc.c b/sys/kern/sysv_ipc.c
--- a/sys/kern/sysv_ipc.c
+++ b/sys/kern/sysv_ipc.c
@@ -36,7 +36,6 @@
  * $NetBSD: sysv_ipc.c,v 1.9 1995/06/02 19:04:22 mycroft Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_sysvipc.h"
 
 #include <sys/param.h>
diff --git a/sys/kern/sysv_msg.c b/sys/kern/sysv_msg.c
--- a/sys/kern/sysv_msg.c
+++ b/sys/kern/sysv_msg.c
@@ -55,7 +55,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_sysvipc.h"
 
 #include <sys/param.h>
diff --git a/sys/kern/sysv_sem.c b/sys/kern/sysv_sem.c
--- a/sys/kern/sysv_sem.c
+++ b/sys/kern/sysv_sem.c
@@ -44,7 +44,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_sysvipc.h"
 
 #include <sys/param.h>
diff --git a/sys/kern/sysv_shm.c b/sys/kern/sysv_shm.c
--- a/sys/kern/sysv_shm.c
+++ b/sys/kern/sysv_shm.c
@@ -68,7 +68,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_sysvipc.h"
 
 #include <sys/param.h>