diff --git a/tests/sys/net/if_bridge_test.sh b/tests/sys/net/if_bridge_test.sh
index c51321187018..afb260a86cc3 100755
--- a/tests/sys/net/if_bridge_test.sh
+++ b/tests/sys/net/if_bridge_test.sh
@@ -1,73 +1,142 @@
 # $FreeBSD$
 #
 # SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 #
 # Copyright (c) 2020 The FreeBSD Foundation
 #
 # This software was developed by Kristof Provost under sponsorship
 # from the FreeBSD Foundation.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 # 1. Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
 # 2. Redistributions in binary form must reproduce the above copyright
 #    notice, this list of conditions and the following disclaimer in the
 #    documentation and/or other materials provided with the distribution.
 #
 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 # SUCH DAMAGE.
 
 . $(atf_get_srcdir)/../common/vnet.subr
 
 atf_test_case "bridge_transmit_ipv4_unicast" "cleanup"
 bridge_transmit_ipv4_unicast_head()
 {
 	atf_set descr 'bridge_transmit_ipv4_unicast bridging test'
 	atf_set require.user root
 }
 
 bridge_transmit_ipv4_unicast_body()
 {
 	vnet_init
 
 	epair_alcatraz=$(vnet_mkepair)
 	epair_singsing=$(vnet_mkepair)
 
 	vnet_mkjail alcatraz ${epair_alcatraz}b
 	vnet_mkjail singsing ${epair_singsing}b
 
 	jexec alcatraz ifconfig ${epair_alcatraz}b 192.0.2.1/24 up
 	jexec singsing ifconfig ${epair_singsing}b 192.0.2.2/24 up
 
 	bridge=$(vnet_mkbridge)
 
 	ifconfig ${bridge} up
 	ifconfig ${epair_alcatraz}a up
 	ifconfig ${epair_singsing}a up
 	ifconfig ${bridge} addm ${epair_alcatraz}a
 	ifconfig ${bridge} addm ${epair_singsing}a
 
 	atf_check -s exit:0 -o ignore jexec alcatraz ping -c 3 -t 1 192.0.2.2
 	atf_check -s exit:0 -o ignore jexec singsing ping -c 3 -t 1 192.0.2.1
 }
 
 bridge_transmit_ipv4_unicast_cleanup()
 {
 	vnet_cleanup
 }
 
+atf_test_case "stp" "cleanup"
+stp_head()
+{
+	atf_set descr 'Spanning tree test'
+	atf_set require.user root
+	atf_set require.progs jq
+}
+
+stp_body()
+{
+	vnet_init
+
+	epair_one=$(vnet_mkepair)
+	epair_two=$(vnet_mkepair)
+	bridge_a=$(vnet_mkbridge)
+	bridge_b=$(vnet_mkbridge)
+
+	vnet_mkjail a ${bridge_a} ${epair_one}a ${epair_two}a
+	vnet_mkjail b ${bridge_b} ${epair_one}b ${epair_two}b
+
+	jexec a ifconfig ${bridge_a} up
+	jexec a ifconfig ${epair_one}a up
+	jexec a ifconfig ${epair_two}a up
+	jexec a ifconfig ${bridge_a} addm ${epair_one}a
+	jexec a ifconfig ${bridge_a} addm ${epair_two}a
+
+	jexec b ifconfig ${bridge_b} up
+	jexec b ifconfig ${epair_one}b up
+	jexec b ifconfig ${epair_two}b up
+	jexec b ifconfig ${bridge_b} addm ${epair_one}b
+	jexec b ifconfig ${bridge_b} addm ${epair_two}b
+
+	jexec a ifconfig ${bridge_a} 192.0.2.1/24
+
+	# Give the interfaces some time to come up and pass some traffic
+	sleep 5
+
+	# Confirm that there's looping traffic
+	nbr=$(jexec a netstat -I ${bridge_a} --libxo json \
+		| jq ".statistics.interface[0].\"received-packets\"")
+	if [ ${nbr} -lt 100 ]
+	then
+		atf_fail "Expected bridging loop, but found very few packets."
+	fi
+
+	# Enable spanning tree
+	jexec a ifconfig ${bridge_a} stp ${epair_one}a
+	jexec a ifconfig ${bridge_a} stp ${epair_two}a
+	jexec b ifconfig ${bridge_b} stp ${epair_one}b
+	jexec b ifconfig ${bridge_b} stp ${epair_two}b
+
+	# Give STP time to do its thing
+	sleep 5
+
+	a_discard=$(jexec a ifconfig ${bridge_a} | grep discarding)
+	b_discard=$(jexec b ifconfig ${bridge_b} | grep discarding)
+
+	if [ -z "${a_discard}" ] && [ -z "${b_discard}" ]
+	then
+		atf_fail "STP failed to detect bridging loop"
+	fi
+}
+
+stp_cleanup()
+{
+	vnet_cleanup
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case "bridge_transmit_ipv4_unicast"
+	atf_add_test_case "stp"
 }