diff --git a/sys/netinet/accf_data.c b/sys/netinet/accf_data.c
index d5ada4ed12d..9ba1fd1e747 100644
--- a/sys/netinet/accf_data.c
+++ b/sys/netinet/accf_data.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #define ACCEPT_FILTER_MOD
 
 #include <sys/param.h>
diff --git a/sys/netinet/accf_http.c b/sys/netinet/accf_http.c
index f06fd64de57..9b76e3cfd31 100644
--- a/sys/netinet/accf_http.c
+++ b/sys/netinet/accf_http.c
@@ -27,7 +27,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #define ACCEPT_FILTER_MOD
 
 #include <sys/param.h>
diff --git a/sys/netinet/accf_tls.c b/sys/netinet/accf_tls.c
index 9f1ed700047..a0b357fe949 100644
--- a/sys/netinet/accf_tls.c
+++ b/sys/netinet/accf_tls.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #define ACCEPT_FILTER_MOD
 
 #include <sys/param.h>
diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
index dc6ef343662..ff60803f451 100644
--- a/sys/netinet/if_ether.c
+++ b/sys/netinet/if_ether.c
@@ -35,7 +35,6 @@
  *	add "inuse/lock" bit (or ref. count) along with valid bit
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/igmp.c b/sys/netinet/igmp.c
index 299f3c2e02b..ad22efb1649 100644
--- a/sys/netinet/igmp.c
+++ b/sys/netinet/igmp.c
@@ -47,7 +47,6 @@
  * MULTICAST Revision: 3.5.1.4
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/in.c b/sys/netinet/in.c
index 70a61dbf93a..19ab485bc75 100644
--- a/sys/netinet/in.c
+++ b/sys/netinet/in.c
@@ -30,7 +30,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #define IN_HISTORICAL_NETS		/* include class masks */
diff --git a/sys/netinet/in_debug.c b/sys/netinet/in_debug.c
index 7535e99f4d4..513804d5da3 100644
--- a/sys/netinet/in_debug.c
+++ b/sys/netinet/in_debug.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/in_fib.c b/sys/netinet/in_fib.c
index f6bb6bdbb50..0bcda9fdd31 100644
--- a/sys/netinet/in_fib.c
+++ b/sys/netinet/in_fib.c
@@ -27,7 +27,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_route.h"
 
diff --git a/sys/netinet/in_fib_algo.c b/sys/netinet/in_fib_algo.c
index 95621c30006..ab2743034c4 100644
--- a/sys/netinet/in_fib_algo.c
+++ b/sys/netinet/in_fib_algo.c
@@ -25,7 +25,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/in_fib_dxr.c b/sys/netinet/in_fib_dxr.c
index 538cd43a88a..c0e805e6d17 100644
--- a/sys/netinet/in_fib_dxr.c
+++ b/sys/netinet/in_fib_dxr.c
@@ -42,7 +42,6 @@
  * lookups per second on commodity CPUs, IEEE SoftCOM, September 2017, Split
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/in_gif.c b/sys/netinet/in_gif.c
index e25a08bb60c..ebe7a4a6290 100644
--- a/sys/netinet/in_gif.c
+++ b/sys/netinet/in_gif.c
@@ -32,7 +32,6 @@
  *	$KAME: in_gif.c,v 1.54 2001/05/14 14:02:16 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/in_jail.c b/sys/netinet/in_jail.c
index 7b2120f575c..141164f894e 100644
--- a/sys/netinet/in_jail.c
+++ b/sys/netinet/in_jail.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 #include "opt_inet.h"
 #include "opt_inet6.h"
diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c
index b7dae78fb2c..9610ce2fe36 100644
--- a/sys/netinet/in_pcb.c
+++ b/sys/netinet/in_pcb.c
@@ -36,7 +36,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 #include "opt_ipsec.h"
 #include "opt_inet.h"
diff --git a/sys/netinet/in_proto.c b/sys/netinet/in_proto.c
index 42a6cf0b581..3ec515d216f 100644
--- a/sys/netinet/in_proto.c
+++ b/sys/netinet/in_proto.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_mrouting.h"
 #include "opt_ipsec.h"
 #include "opt_inet.h"
diff --git a/sys/netinet/ip_carp.c b/sys/netinet/ip_carp.c
index 4f553b9aac5..d33ac4e9a15 100644
--- a/sys/netinet/ip_carp.c
+++ b/sys/netinet/ip_carp.c
@@ -28,7 +28,6 @@
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_bpf.h"
 #include "opt_inet.h"
 #include "opt_inet6.h"
diff --git a/sys/netinet/ip_divert.c b/sys/netinet/ip_divert.c
index 5a561814cdb..a88497a7101 100644
--- a/sys/netinet/ip_divert.c
+++ b/sys/netinet/ip_divert.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_sctp.h"
diff --git a/sys/netinet/ip_ecn.c b/sys/netinet/ip_ecn.c
index 2f700c43bbf..0166c8b5d9c 100644
--- a/sys/netinet/ip_ecn.c
+++ b/sys/netinet/ip_ecn.c
@@ -36,7 +36,6 @@
  * http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/ip_encap.c b/sys/netinet/ip_encap.c
index 6de799dec1d..d3ca0b19f2f 100644
--- a/sys/netinet/ip_encap.c
+++ b/sys/netinet/ip_encap.c
@@ -58,7 +58,6 @@
  * The code will let you match protocol via src/dst address pair.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/ip_fastfwd.c b/sys/netinet/ip_fastfwd.c
index 51e7c2fbc4b..d3d42afb2d8 100644
--- a/sys/netinet/ip_fastfwd.c
+++ b/sys/netinet/ip_fastfwd.c
@@ -67,7 +67,6 @@
  * is being followed here.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ipstealth.h"
 #include "opt_sctp.h"
 
diff --git a/sys/netinet/ip_gre.c b/sys/netinet/ip_gre.c
index 01a6ef4cd67..8175155cc2c 100644
--- a/sys/netinet/ip_gre.c
+++ b/sys/netinet/ip_gre.c
@@ -34,7 +34,6 @@
  * $NetBSD: ip_gre.c,v 1.29 2003/09/05 23:02:43 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/ip_icmp.c b/sys/netinet/ip_icmp.c
index fc0848b2c94..adf69c47aed 100644
--- a/sys/netinet/ip_icmp.c
+++ b/sys/netinet/ip_icmp.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/ip_id.c b/sys/netinet/ip_id.c
index 738b7eceb44..4a224a157a5 100644
--- a/sys/netinet/ip_id.c
+++ b/sys/netinet/ip_id.c
@@ -26,7 +26,6 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 /*
  * IP ID generation is a fascinating topic.
  *
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 4d614dfeb0a..6ddec672642 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_bootp.h"
 #include "opt_inet.h"
 #include "opt_ipstealth.h"
diff --git a/sys/netinet/ip_mroute.c b/sys/netinet/ip_mroute.c
index d30bd42ec57..f9efdc41988 100644
--- a/sys/netinet/ip_mroute.c
+++ b/sys/netinet/ip_mroute.c
@@ -67,7 +67,6 @@
  * TODO: Sync ip6_mroute.c with this file.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_mrouting.h"
 
diff --git a/sys/netinet/ip_options.c b/sys/netinet/ip_options.c
index a9d6836d9e9..285bdad4627 100644
--- a/sys/netinet/ip_options.c
+++ b/sys/netinet/ip_options.c
@@ -31,7 +31,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ipstealth.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c
index ef08b9cfd3d..a6b29c6a761 100644
--- a/sys/netinet/ip_output.c
+++ b/sys/netinet/ip_output.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_ipsec.h"
 #include "opt_kern_tls.h"
diff --git a/sys/netinet/ip_reass.c b/sys/netinet/ip_reass.c
index 177069f5e01..510a300ed6e 100644
--- a/sys/netinet/ip_reass.c
+++ b/sys/netinet/ip_reass.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_rss.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/sctp_crc32.c b/sys/netinet/sctp_crc32.c
index 60d8bc38735..c9647ceccc6 100644
--- a/sys/netinet/sctp_crc32.c
+++ b/sys/netinet/sctp_crc32.c
@@ -32,7 +32,6 @@
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_sctp.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/sctp_module.c b/sys/netinet/sctp_module.c
index 2e229658efd..4af7776433c 100644
--- a/sys/netinet/sctp_module.c
+++ b/sys/netinet/sctp_module.c
@@ -28,7 +28,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/sctp_syscalls.c b/sys/netinet/sctp_syscalls.c
index 9d85576e259..80d1d58a786 100644
--- a/sys/netinet/sctp_syscalls.c
+++ b/sys/netinet/sctp_syscalls.c
@@ -28,7 +28,6 @@
  *
  */
 
-#include <sys/cdefs.h>
 #include "opt_capsicum.h"
 #include "opt_sctp.h"
 #include "opt_ktrace.h"
diff --git a/sys/netinet/tcp_ecn.c b/sys/netinet/tcp_ecn.c
index 5332b3caf95..31b9418c5fc 100644
--- a/sys/netinet/tcp_ecn.c
+++ b/sys/netinet/tcp_ecn.c
@@ -54,7 +54,6 @@
  * https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-09
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_fastopen.c b/sys/netinet/tcp_fastopen.c
index 609637b83df..fb1386c03d2 100644
--- a/sys/netinet/tcp_fastopen.c
+++ b/sys/netinet/tcp_fastopen.c
@@ -163,7 +163,6 @@
  *
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/tcp_hostcache.c b/sys/netinet/tcp_hostcache.c
index df639876a85..e5c20b6f247 100644
--- a/sys/netinet/tcp_hostcache.c
+++ b/sys/netinet/tcp_hostcache.c
@@ -65,7 +65,6 @@
  * followed here.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet6.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet/tcp_hpts.c b/sys/netinet/tcp_hpts.c
index c54459bb5f0..29a55c1a7e3 100644
--- a/sys/netinet/tcp_hpts.c
+++ b/sys/netinet/tcp_hpts.c
@@ -23,7 +23,6 @@
  * SUCH DAMAGE.
  *
  */
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_rss.h"
diff --git a/sys/netinet/tcp_hpts_test.c b/sys/netinet/tcp_hpts_test.c
index c5dc9cb5b03..61082adc906 100644
--- a/sys/netinet/tcp_hpts_test.c
+++ b/sys/netinet/tcp_hpts_test.c
@@ -26,7 +26,6 @@
  */
 
 #include <tests/ktest.h>
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include <sys/param.h>
 #include <sys/bus.h>
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 9c58c2815d1..85ab26351f6 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -47,7 +47,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_log_buf.c b/sys/netinet/tcp_log_buf.c
index 473c534ef83..4505171d94d 100644
--- a/sys/netinet/tcp_log_buf.c
+++ b/sys/netinet/tcp_log_buf.c
@@ -27,7 +27,6 @@
  *
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_ddb.h"
 #include <sys/param.h>
diff --git a/sys/netinet/tcp_lro.c b/sys/netinet/tcp_lro.c
index 9b5baf11585..3b04d757c0f 100644
--- a/sys/netinet/tcp_lro.c
+++ b/sys/netinet/tcp_lro.c
@@ -32,7 +32,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_lro_hpts.c b/sys/netinet/tcp_lro_hpts.c
index ac1a27a4290..99989d2833c 100644
--- a/sys/netinet/tcp_lro_hpts.c
+++ b/sys/netinet/tcp_lro_hpts.c
@@ -24,7 +24,6 @@
  * SUCH DAMAGE.
  *
  */
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_offload.c b/sys/netinet/tcp_offload.c
index 6a362484d46..20bc1df9e15 100644
--- a/sys/netinet/tcp_offload.c
+++ b/sys/netinet/tcp_offload.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index 208f72c4661..23085f67d5f 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_ratelimit.c b/sys/netinet/tcp_ratelimit.c
index a0e837cc7d7..ad5fdb25205 100644
--- a/sys/netinet/tcp_ratelimit.c
+++ b/sys/netinet/tcp_ratelimit.c
@@ -31,7 +31,6 @@
  * Author: Randall Stewart <rrs@netflix.com>
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_reass.c b/sys/netinet/tcp_reass.c
index 5f73e83dc8a..d1a70e4db3a 100644
--- a/sys/netinet/tcp_reass.c
+++ b/sys/netinet/tcp_reass.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c
index 6e08ad2796a..13cc7b0de15 100644
--- a/sys/netinet/tcp_sack.c
+++ b/sys/netinet/tcp_sack.c
@@ -69,7 +69,6 @@
  * Research Laboratory (NRL).
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index b6f428b279b..6b0aa76527f 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c
index 6c072e0fec3..056542bc43d 100644
--- a/sys/netinet/tcp_syncache.c
+++ b/sys/netinet/tcp_syncache.c
@@ -32,7 +32,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c
index 57c57666fa3..b409daf5895 100644
--- a/sys/netinet/tcp_timer.c
+++ b/sys/netinet/tcp_timer.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_rss.h"
diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c
index ce63fcf9ffc..3afa3c0ac1c 100644
--- a/sys/netinet/tcp_timewait.c
+++ b/sys/netinet/tcp_timewait.c
@@ -29,7 +29,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet/tcp_usrreq.c b/sys/netinet/tcp_usrreq.c
index aeb28cd6a14..a0658e18fb1 100644
--- a/sys/netinet/tcp_usrreq.c
+++ b/sys/netinet/tcp_usrreq.c
@@ -35,7 +35,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 #include "opt_inet.h"
 #include "opt_inet6.h"
diff --git a/sys/netinet/toecore.c b/sys/netinet/toecore.c
index 4203029ff7c..1c4e89069a4 100644
--- a/sys/netinet/toecore.c
+++ b/sys/netinet/toecore.c
@@ -27,7 +27,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c
index f1d952037d5..75782765bc9 100644
--- a/sys/netinet/udp_usrreq.c
+++ b/sys/netinet/udp_usrreq.c
@@ -36,7 +36,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/dest6.c b/sys/netinet6/dest6.c
index 85ce894c40c..e8b60fe7910 100644
--- a/sys/netinet6/dest6.c
+++ b/sys/netinet6/dest6.c
@@ -31,7 +31,6 @@
  *	$KAME: dest6.c,v 1.59 2003/07/11 13:21:16 t-momose Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/frag6.c b/sys/netinet6/frag6.c
index f6bb6e94ed0..7d71e132793 100644
--- a/sys/netinet6/frag6.c
+++ b/sys/netinet6/frag6.c
@@ -32,7 +32,6 @@
  *	$KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_rss.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet6/icmp6.c b/sys/netinet6/icmp6.c
index f98381499b2..c05850f1477 100644
--- a/sys/netinet6/icmp6.c
+++ b/sys/netinet6/icmp6.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #define	MBUF_PRIVATE	/* XXXRW: Optimisation tries to avoid M_EXT mbufs */
 
 #include "opt_inet.h"
diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index b98703bdfbf..f2a03258534 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/in6_fib.c b/sys/netinet6/in6_fib.c
index 3e8b8ccce7a..95094a1ace7 100644
--- a/sys/netinet6/in6_fib.c
+++ b/sys/netinet6/in6_fib.c
@@ -27,7 +27,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_route.h"
diff --git a/sys/netinet6/in6_fib_algo.c b/sys/netinet6/in6_fib_algo.c
index ef5cfc6d5ef..47c1f7d2078 100644
--- a/sys/netinet6/in6_fib_algo.c
+++ b/sys/netinet6/in6_fib_algo.c
@@ -25,7 +25,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet6.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet6/in6_gif.c b/sys/netinet6/in6_gif.c
index 2bab1c57ce2..5159faa1e2e 100644
--- a/sys/netinet6/in6_gif.c
+++ b/sys/netinet6/in6_gif.c
@@ -32,7 +32,6 @@
  *	$KAME: in6_gif.c,v 1.49 2001/05/14 14:02:17 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/in6_jail.c b/sys/netinet6/in6_jail.c
index 5abdef9ab71..84057f3f964 100644
--- a/sys/netinet6/in6_jail.c
+++ b/sys/netinet6/in6_jail.c
@@ -26,7 +26,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_ddb.h"
 #include "opt_inet.h"
 #include "opt_inet6.h"
diff --git a/sys/netinet6/in6_mcast.c b/sys/netinet6/in6_mcast.c
index a6186568ecb..613bd14428b 100644
--- a/sys/netinet6/in6_mcast.c
+++ b/sys/netinet6/in6_mcast.c
@@ -34,7 +34,6 @@
  * Normative references: RFC 2292, RFC 3492, RFC 3542, RFC 3678, RFC 3810.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet6.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet6/in6_pcb.c b/sys/netinet6/in6_pcb.c
index dfda0c60c0b..f2eb0016169 100644
--- a/sys/netinet6/in6_pcb.c
+++ b/sys/netinet6/in6_pcb.c
@@ -64,7 +64,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/in6_proto.c b/sys/netinet6/in6_proto.c
index f567b42b42c..a566ca6b0fb 100644
--- a/sys/netinet6/in6_proto.c
+++ b/sys/netinet6/in6_proto.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/in6_src.c b/sys/netinet6/in6_src.c
index 3e55c6e5fc0..5171bc1d4ea 100644
--- a/sys/netinet6/in6_src.c
+++ b/sys/netinet6/in6_src.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include <sys/param.h>
diff --git a/sys/netinet6/ip6_fastfwd.c b/sys/netinet6/ip6_fastfwd.c
index 7139267722b..9298b8ea9a4 100644
--- a/sys/netinet6/ip6_fastfwd.c
+++ b/sys/netinet6/ip6_fastfwd.c
@@ -24,7 +24,6 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet6.h"
 #include "opt_ipstealth.h"
 #include "opt_sctp.h"
diff --git a/sys/netinet6/ip6_forward.c b/sys/netinet6/ip6_forward.c
index f6c09b0ac7b..9823366b015 100644
--- a/sys/netinet6/ip6_forward.c
+++ b/sys/netinet6/ip6_forward.c
@@ -31,7 +31,6 @@
  *	$KAME: ip6_forward.c,v 1.69 2001/05/17 03:48:30 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/ip6_gre.c b/sys/netinet6/ip6_gre.c
index 9ba45cb294e..952b132e4cf 100644
--- a/sys/netinet6/ip6_gre.c
+++ b/sys/netinet6/ip6_gre.c
@@ -24,7 +24,6 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/ip6_id.c b/sys/netinet6/ip6_id.c
index 7c39bcf943b..73e48d8c840 100644
--- a/sys/netinet6/ip6_id.c
+++ b/sys/netinet6/ip6_id.c
@@ -63,7 +63,6 @@
  * $OpenBSD: ip6_id.c,v 1.3 2003/12/12 06:57:12 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 /*
  * seed = random (bits - 1) bit
  * n = prime, g0 = generator to n,
diff --git a/sys/netinet6/ip6_input.c b/sys/netinet6/ip6_input.c
index 99dad1e7c30..380391fd71f 100644
--- a/sys/netinet6/ip6_input.c
+++ b/sys/netinet6/ip6_input.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/ip6_mroute.c b/sys/netinet6/ip6_mroute.c
index f3c68d61f24..4473d3931af 100644
--- a/sys/netinet6/ip6_mroute.c
+++ b/sys/netinet6/ip6_mroute.c
@@ -78,7 +78,6 @@
  * MROUTING Revision: 3.5.1.2 + PIM-SMv2 (pimd) Support
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet6.h"
 
 #include <sys/param.h>
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index 6299ce6e146..8ade50b1356 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -60,7 +60,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/mld6.c b/sys/netinet6/mld6.c
index 5dfe48908a4..fd0a1503a6e 100644
--- a/sys/netinet6/mld6.c
+++ b/sys/netinet6/mld6.c
@@ -63,7 +63,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index 00df5efcef9..a62b26d2725 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -31,7 +31,6 @@
  *	$KAME: nd6.c,v 1.144 2001/05/24 07:44:00 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_route.h"
diff --git a/sys/netinet6/nd6_nbr.c b/sys/netinet6/nd6_nbr.c
index 29151b29a07..aa7cb3b4197 100644
--- a/sys/netinet6/nd6_nbr.c
+++ b/sys/netinet6/nd6_nbr.c
@@ -31,7 +31,6 @@
  *	$KAME: nd6_nbr.c,v 1.86 2002/01/21 02:33:04 jinmei Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
diff --git a/sys/netinet6/nd6_rtr.c b/sys/netinet6/nd6_rtr.c
index 10f0342f2bc..224cd7e56b4 100644
--- a/sys/netinet6/nd6_rtr.c
+++ b/sys/netinet6/nd6_rtr.c
@@ -31,7 +31,6 @@
  *	$KAME: nd6_rtr.c,v 1.111 2001/04/27 01:37:15 jinmei Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/route6.c b/sys/netinet6/route6.c
index e570c77db3d..9cf5ecb519b 100644
--- a/sys/netinet6/route6.c
+++ b/sys/netinet6/route6.c
@@ -31,7 +31,6 @@
  *	$KAME: route6.c,v 1.24 2001/03/14 03:07:05 itojun Exp $
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 
diff --git a/sys/netinet6/udp6_usrreq.c b/sys/netinet6/udp6_usrreq.c
index 1a32365f5d1..ca7c9549751 100644
--- a/sys/netinet6/udp6_usrreq.c
+++ b/sys/netinet6/udp6_usrreq.c
@@ -67,7 +67,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"