diff --git a/sys/security/mac/mac_internal.h b/sys/security/mac/mac_internal.h
--- a/sys/security/mac/mac_internal.h
+++ b/sys/security/mac/mac_internal.h
@@ -56,13 +56,6 @@
 #include <sys/lock.h>
 #include <sys/rmlock.h>
 
-/*
- * MAC Framework sysctl namespace.
- */
-#ifdef SYSCTL_DECL
-SYSCTL_DECL(_security_mac);
-#endif /* SYSCTL_DECL */
-
 /*
  * MAC Framework SDT DTrace probe namespace, macros for declaring entry
  * point probes, macros for invoking them.
diff --git a/sys/security/mac/mac_policy.h b/sys/security/mac/mac_policy.h
--- a/sys/security/mac/mac_policy.h
+++ b/sys/security/mac/mac_policy.h
@@ -1064,4 +1064,19 @@
 intptr_t	mac_label_get(struct label *l, int slot);
 void		mac_label_set(struct label *l, int slot, intptr_t v);
 
+/*
+ * Common MAC Framework's sysctl and jail parameters' sysctl nodes' declarations.
+ *
+ * Headers <sys/jail.h> and <sys/sysctl.h> normally have to be included before
+ * this header as style(9) hints to.  If they weren't, just forego the
+ * corresponding declarations, assuming they are not needed.
+ */
+#ifdef SYSCTL_DECL
+SYSCTL_DECL(_security_mac);
+#endif
+
+#ifdef SYSCTL_JAIL_PARAM_DECL
+SYSCTL_JAIL_PARAM_DECL(mac);
+#endif
+
 #endif /* !_SECURITY_MAC_MAC_POLICY_H_ */
diff --git a/sys/security/mac_biba/mac_biba.c b/sys/security/mac_biba/mac_biba.c
--- a/sys/security/mac_biba/mac_biba.c
+++ b/sys/security/mac_biba/mac_biba.c
@@ -88,8 +88,6 @@
 #include <security/mac/mac_policy.h>
 #include <security/mac_biba/mac_biba.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, biba,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_biba policy controls");
diff --git a/sys/security/mac_bsdextended/mac_bsdextended.c b/sys/security/mac_bsdextended/mac_bsdextended.c
--- a/sys/security/mac_bsdextended/mac_bsdextended.c
+++ b/sys/security/mac_bsdextended/mac_bsdextended.c
@@ -68,8 +68,6 @@
 
 static struct mtx ugidfw_mtx;
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, bsdextended,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD extended BSD MAC policy controls");
diff --git a/sys/security/mac_grantbylabel/mac_grantbylabel.c b/sys/security/mac_grantbylabel/mac_grantbylabel.c
--- a/sys/security/mac_grantbylabel/mac_grantbylabel.c
+++ b/sys/security/mac_grantbylabel/mac_grantbylabel.c
@@ -49,7 +49,6 @@
 
 #define MAC_GRANTBYLABEL_FULLNAME   "MAC/grantbylabel"
 
-SYSCTL_DECL(_security_mac);
 SYSCTL_NODE(_security_mac, OID_AUTO, grantbylabel, CTLFLAG_RW, 0,
     "MAC/grantbylabel policy controls");
 
diff --git a/sys/security/mac_ifoff/mac_ifoff.c b/sys/security/mac_ifoff/mac_ifoff.c
--- a/sys/security/mac_ifoff/mac_ifoff.c
+++ b/sys/security/mac_ifoff/mac_ifoff.c
@@ -58,8 +58,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, ifoff,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_ifoff policy controls");
diff --git a/sys/security/mac_ipacl/mac_ipacl.c b/sys/security/mac_ipacl/mac_ipacl.c
--- a/sys/security/mac_ipacl/mac_ipacl.c
+++ b/sys/security/mac_ipacl/mac_ipacl.c
@@ -70,8 +70,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, ipacl, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_ipacl policy controls");
 
diff --git a/sys/security/mac_lomac/mac_lomac.c b/sys/security/mac_lomac/mac_lomac.c
--- a/sys/security/mac_lomac/mac_lomac.c
+++ b/sys/security/mac_lomac/mac_lomac.c
@@ -89,8 +89,6 @@
 	struct mtx mtx;
 };
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, lomac,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_lomac policy controls");
diff --git a/sys/security/mac_mls/mac_mls.c b/sys/security/mac_mls/mac_mls.c
--- a/sys/security/mac_mls/mac_mls.c
+++ b/sys/security/mac_mls/mac_mls.c
@@ -89,8 +89,6 @@
 #include <security/mac/mac_policy.h>
 #include <security/mac_mls/mac_mls.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, mls,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_mls policy controls");
diff --git a/sys/security/mac_ntpd/mac_ntpd.c b/sys/security/mac_ntpd/mac_ntpd.c
--- a/sys/security/mac_ntpd/mac_ntpd.c
+++ b/sys/security/mac_ntpd/mac_ntpd.c
@@ -34,8 +34,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, ntpd,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "mac_ntpd policy controls");
diff --git a/sys/security/mac_partition/mac_partition.c b/sys/security/mac_partition/mac_partition.c
--- a/sys/security/mac_partition/mac_partition.c
+++ b/sys/security/mac_partition/mac_partition.c
@@ -61,8 +61,6 @@
 #include <security/mac/mac_policy.h>
 #include <security/mac_partition/mac_partition.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, partition,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_partition policy controls");
diff --git a/sys/security/mac_pimd/mac_pimd.c b/sys/security/mac_pimd/mac_pimd.c
--- a/sys/security/mac_pimd/mac_pimd.c
+++ b/sys/security/mac_pimd/mac_pimd.c
@@ -35,8 +35,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, pimd,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "mac_pimd policy controls");
diff --git a/sys/security/mac_portacl/mac_portacl.c b/sys/security/mac_portacl/mac_portacl.c
--- a/sys/security/mac_portacl/mac_portacl.c
+++ b/sys/security/mac_portacl/mac_portacl.c
@@ -79,8 +79,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, portacl,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_portacl policy controls");
diff --git a/sys/security/mac_priority/mac_priority.c b/sys/security/mac_priority/mac_priority.c
--- a/sys/security/mac_priority/mac_priority.c
+++ b/sys/security/mac_priority/mac_priority.c
@@ -35,8 +35,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, priority,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "mac_priority policy controls");
diff --git a/sys/security/mac_seeotheruids/mac_seeotheruids.c b/sys/security/mac_seeotheruids/mac_seeotheruids.c
--- a/sys/security/mac_seeotheruids/mac_seeotheruids.c
+++ b/sys/security/mac_seeotheruids/mac_seeotheruids.c
@@ -59,8 +59,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, seeotheruids,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_seeotheruids policy controls");
diff --git a/sys/security/mac_stub/mac_stub.c b/sys/security/mac_stub/mac_stub.c
--- a/sys/security/mac_stub/mac_stub.c
+++ b/sys/security/mac_stub/mac_stub.c
@@ -88,8 +88,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, stub,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_stub policy controls");
diff --git a/sys/security/mac_test/mac_test.c b/sys/security/mac_test/mac_test.c
--- a/sys/security/mac_test/mac_test.c
+++ b/sys/security/mac_test/mac_test.c
@@ -78,8 +78,6 @@
 
 #include <security/mac/mac_policy.h>
 
-SYSCTL_DECL(_security_mac);
-
 static SYSCTL_NODE(_security_mac, OID_AUTO, test,
     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "TrustedBSD mac_test policy controls");
diff --git a/sys/security/mac_veriexec/mac_veriexec.c b/sys/security/mac_veriexec/mac_veriexec.c
--- a/sys/security/mac_veriexec/mac_veriexec.c
+++ b/sys/security/mac_veriexec/mac_veriexec.c
@@ -81,8 +81,6 @@
 static int sysctl_mac_veriexec_db(SYSCTL_HANDLER_ARGS);
 static struct mac_policy_ops mac_veriexec_ops;
 
-SYSCTL_DECL(_security_mac);
-
 SYSCTL_NODE(_security_mac, OID_AUTO, veriexec, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
     "MAC/veriexec policy controls");