diff --git a/libexec/rc/rc b/libexec/rc/rc
--- a/libexec/rc/rc
+++ b/libexec/rc/rc
@@ -83,9 +83,9 @@
 trap "_rc_conf_loaded=false; load_rc_config" ALRM
 
 skip="-s nostart"
-if [ `/sbin/sysctl -n security.jail.jailed` -eq 1 ]; then
+if check_jail jailed; then
 	skip="$skip -s nojail"
-	if [ `/sbin/sysctl -n security.jail.vnet` -ne 1 ]; then
+	if ! check_jail vnet; then
 		skip="$skip -s nojailvnet"
 	fi
 fi
diff --git a/libexec/rc/rc.d/hostname b/libexec/rc/rc.d/hostname
--- a/libexec/rc/rc.d/hostname
+++ b/libexec/rc/rc.d/hostname
@@ -42,8 +42,8 @@
 	# If we are not inside a jail, set the host name.
 	# If we are inside a jail, set the host name if it is permitted.
 	#
-	if [ `$SYSCTL_N security.jail.jailed` -eq 1 ]; then
-		if [ `$SYSCTL_N security.jail.set_hostname_allowed` -eq 0 ]; then
+	if check_jail jailed; then
+		if ! check_jail set_hostname_allowed; then
 			return
 		fi
 	else
diff --git a/libexec/rc/rc.d/routing b/libexec/rc/rc.d/routing
--- a/libexec/rc/rc.d/routing
+++ b/libexec/rc/rc.d/routing
@@ -331,7 +331,7 @@
 
 	# copied from /etc/rc
 	skip="-s nostart"
-	if [ `/sbin/sysctl -n security.jail.jailed` -eq 1 ]; then
+	if check_jail jailed; then
 		skip="$skip -s nojail"
 	fi
 	[ -n "$local_startup" ] && find_local_scripts_new
diff --git a/libexec/rc/rc.d/zfs b/libexec/rc/rc.d/zfs
--- a/libexec/rc/rc.d/zfs
+++ b/libexec/rc/rc.d/zfs
@@ -18,7 +18,7 @@
 
 zfs_start_jail()
 {
-	if [ `$SYSCTL_N security.jail.mount_allowed` -eq 1 ]; then
+	if check_jail mount_allowed; then
 		zfs mount -a
 	fi
 }
@@ -34,7 +34,7 @@
 
 zfs_start()
 {
-	if [ `$SYSCTL_N security.jail.jailed` -eq 1 ]; then
+	if check_jail jailed; then
 		zfs_start_jail
 	else
 		zfs_start_main
@@ -54,7 +54,7 @@
 
 zfs_stop_jail()
 {
-	if [ `$SYSCTL_N security.jail.mount_allowed` -eq 1 ]; then
+	if check_jail mount_allowed; then
 		zfs unmount -a
 	fi
 }
@@ -67,7 +67,7 @@
 
 zfs_stop()
 {
-	if [ `$SYSCTL_N security.jail.jailed` -eq 1 ]; then
+	if check_jail jailed; then
 		zfs_stop_jail
 	else
 		zfs_stop_main
diff --git a/libexec/rc/rc.d/zfsbe b/libexec/rc/rc.d/zfsbe
--- a/libexec/rc/rc.d/zfsbe
+++ b/libexec/rc/rc.d/zfsbe
@@ -64,7 +64,7 @@
 
 be_start()
 {
-	if [ `$SYSCTL_N security.jail.jailed` -eq 1 ]; then
+	if check_jail jailed; then
 		:
 	else
 		mount -p | while read _dev _mp _type _rest; do
diff --git a/libexec/rc/rc.shutdown b/libexec/rc/rc.shutdown
--- a/libexec/rc/rc.shutdown
+++ b/libexec/rc/rc.shutdown
@@ -83,9 +83,9 @@
 # and perform the operation
 #
 rcorder_opts="-k shutdown"
-if [ `/sbin/sysctl -n security.jail.jailed` -eq 1 ]; then
+if check_jail jailed; then
 	rcorder_opts="$rcorder_opts -s nojail"
-	if [ `/sbin/sysctl -n security.jail.vnet` -ne 1 ]; then
+	if ! check_jail vnet; then
 		rcorder_opts="$rcorder_opts -s nojailvnet"
 	fi
 fi
diff --git a/libexec/rc/rc.subr b/libexec/rc/rc.subr
--- a/libexec/rc/rc.subr
+++ b/libexec/rc/rc.subr
@@ -1658,7 +1658,7 @@
 		start)
 			# We cannot use protect(1) inside jails.
 			if [ -n "$_oomprotect" ] && [ -f "${PROTECT}" ] &&
-			    [ "$(sysctl -n security.jail.jailed)" -eq 0 ]; then
+			    ! check_jail jailed; then
 				[ -z "${rc_pid}" ] && eval $_pidcmd
 				case $_oomprotect in
 				[Aa][Ll][Ll])