diff --git a/tests/sys/netpfil/common/pft_ping.py b/tests/sys/netpfil/common/pft_ping.py
--- a/tests/sys/netpfil/common/pft_ping.py
+++ b/tests/sys/netpfil/common/pft_ping.py
@@ -116,7 +116,10 @@
 	return True
 
 def check_ping_reply(args, packet):
-	return check_ping4_reply(args, packet)
+	if args.ip6:
+		return check_ping6_reply(args, packet)
+	else:
+		return check_ping4_reply(args, packet)
 
 def check_ping4_reply(args, packet):
 	"""
@@ -144,6 +147,29 @@
 
 	return True
 
+def check_ping6_reply(args, packet):
+	"""
+	Check that this is a reply to the ping request we sent
+	"""
+	dst_ip = args.to[0]
+
+	ip = packet.getlayer(sp.IPv6)
+	if not ip:
+		return False
+	if ip.src != dst_ip:
+		return False
+
+	icmp = packet.getlayer(sp.ICMPv6EchoReply)
+	if not icmp:
+		print("No echo reply!")
+		return False
+
+	if icmp.data != PAYLOAD_MAGIC:
+		print("data mismatch")
+		return False
+
+	return True
+
 def ping(send_if, dst_ip, args):
 	ether = sp.Ether()
 	ip = sp.IP(dst=dst_ip)
diff --git a/tests/sys/netpfil/pf/killstate.sh b/tests/sys/netpfil/pf/killstate.sh
--- a/tests/sys/netpfil/pf/killstate.sh
+++ b/tests/sys/netpfil/pf/killstate.sh
@@ -101,6 +101,78 @@
 	pft_cleanup
 }
 
+atf_test_case "v6" "cleanup"
+v6_head()
+{
+	atf_set descr 'Test killing states by IPv6 address'
+	atf_set require.user root
+	atf_set require.progs scapy
+}
+
+v6_body()
+{
+	pft_init
+
+	epair=$(vnet_mkepair)
+	ifconfig ${epair}a inet6 2001:db8::1/64 up no_dad
+
+	vnet_mkjail alcatraz ${epair}b
+	jexec alcatraz ifconfig ${epair}b inet6 2001:db8::2/64 up no_dad
+	jexec alcatraz pfctl -e
+
+	pft_set_rules alcatraz "block all" \
+		"pass in proto icmp6"
+
+	# Sanity check & establish state
+	# Note: use pft_ping so we always use the same ID, so pf considers all
+	# echo requests part of the same flow.
+	atf_check -s exit:0 -o ignore ${common_dir}/pft_ping.py \
+		--ip6 \
+		--sendif ${epair}a \
+		--to 2001:db8::2 \
+		--replyif ${epair}a
+
+	# Change rules to now deny the ICMP traffic
+	pft_set_rules noflush alcatraz "block all"
+
+	# Established state means we can still ping alcatraz
+	atf_check -s exit:0 -o ignore ${common_dir}/pft_ping.py \
+		--ip6 \
+		--sendif ${epair}a \
+		--to 2001:db8::2 \
+		--replyif ${epair}a
+
+	# Killing with the wrong IP doesn't affect our state
+	jexec alcatraz pfctl -k 2001:db8::3
+	atf_check -s exit:0 -o ignore ${common_dir}/pft_ping.py \
+		--ip6 \
+		--sendif ${epair}a \
+		--to 2001:db8::2 \
+		--replyif ${epair}a
+
+	# Killing with one correct address and one incorrect doesn't kill the state
+	jexec alcatraz pfctl -k 2001:db8::1 -k 2001:db8::3
+	atf_check -s exit:0 -o ignore ${common_dir}/pft_ping.py \
+		--ip6 \
+		--sendif ${epair}a \
+		--to 2001:db8::2 \
+		--replyif ${epair}a
+
+	# Killing with correct address does remove the state
+	jexec alcatraz pfctl -k 2001:db8::1
+	atf_check -s exit:1 -o ignore ${common_dir}/pft_ping.py \
+		--ip6 \
+		--sendif ${epair}a \
+		--to 2001:db8::2 \
+		--replyif ${epair}a
+
+}
+
+v6_cleanup()
+{
+	pft_cleanup
+}
+
 atf_test_case "label" "cleanup"
 label_head()
 {
@@ -171,5 +243,6 @@
 atf_init_test_cases()
 {
 	atf_add_test_case "v4"
+	atf_add_test_case "v6"
 	atf_add_test_case "label"
 }