diff --git a/regress/Makefile b/regress/Makefile
index c920661ae..58bcb38b6 100644
--- a/regress/Makefile
+++ b/regress/Makefile
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.77 2015/01/20 22:58:57 djm Exp $
+#	$OpenBSD: Makefile,v 1.78 2015/01/26 06:12:18 djm Exp $
 
 REGRESS_TARGETS=	unit t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t-exec
 tests:		$(REGRESS_TARGETS)
@@ -68,7 +68,8 @@ LTESTS= 	connect \
 		multipubkey \
 		limit-keytype \
 		hostkey-agent \
-		keygen-knownhosts
+		keygen-knownhosts \
+		hostkey-rotate
 
 
 #		dhgex \
diff --git a/regress/hostkey-rotate.sh b/regress/hostkey-rotate.sh
new file mode 100644
index 000000000..d964b35c2
--- /dev/null
+++ b/regress/hostkey-rotate.sh
@@ -0,0 +1,129 @@
+#	$OpenBSD: hostkey-rotate.sh,v 1.1 2015/01/26 06:12:18 djm Exp $
+#	Placed in the Public Domain.
+
+tid="hostkey rotate"
+
+# Need full names here since they are used in HostKeyAlgorithms
+HOSTKEY_TYPES="ecdsa-sha2-nistp256 ssh-ed25519 ssh-rsa ssh-dss"
+
+rm -f $OBJ/hkr.* $OBJ/ssh_proxy.orig
+
+grep -vi 'hostkey' $OBJ/sshd_proxy > $OBJ/sshd_proxy.orig
+echo "UpdateHostkeys=yes" >> $OBJ/ssh_proxy
+rm $OBJ/known_hosts
+
+trace "prepare hostkeys"
+nkeys=0
+all_algs=""
+for k in `ssh -Q key-plain` ; do
+	${SSHKEYGEN} -qt $k -f $OBJ/hkr.$k -N '' || fatal "ssh-keygen $k"
+	echo "Hostkey $OBJ/hkr.${k}" >> $OBJ/sshd_proxy.orig
+	nkeys=`expr $nkeys + 1`
+	test "x$all_algs" = "x" || all_algs="${all_algs},"
+	all_algs="${all_algs}$k"
+done
+
+dossh() {
+	# All ssh should succeed in this test
+	${SSH} -F $OBJ/ssh_proxy "$@" x true || fail "ssh $@ failed"
+}
+
+expect_nkeys() {
+	_expected=$1
+	_message=$2
+	_n=`wc -l $OBJ/known_hosts | awk '{ print $1 }'` || fatal "wc failed"
+	[ "x$_n" = "x$_expected" ] || fail "$_message (got $_n wanted $_expected)"
+}
+
+check_key_present() {
+	_type=$1
+	_kfile=$2
+	_prog='print $2 " " $3'
+	test "x$_kfile" = "x" && _kfile="$OBJ/hkr.${_type}.pub"
+	_ktext=`awk "/ $_type / { $_prog }" < $OBJ/known_hosts` || \
+		fatal "awk failed"
+	grep -q "$_ktext" $_kfile
+}
+
+cp $OBJ/sshd_proxy.orig $OBJ/sshd_proxy
+
+# Connect to sshd with StrictHostkeyChecking=no
+verbose "learn hostkey with StrictHostKeyChecking=no"
+>$OBJ/known_hosts
+dossh -oHostKeyAlgorithms=ssh-ed25519 -oStrictHostKeyChecking=no
+# Verify no additional keys learned
+expect_nkeys 1 "unstrict connect keys"
+check_key_present ssh-ed25519 || fail "unstrict didn't learn key"
+
+# Connect to sshd as usual
+verbose "learn additional hostkeys"
+dossh -oStrictHostKeyChecking=yes
+# Check that other keys learned
+expect_nkeys $nkeys "learn hostkeys"
+check_key_present ssh-rsa || fail "didn't learn keys"
+
+# Check each key type
+for k in `ssh -Q key-plain` ; do
+	verbose "learn additional hostkeys, type=$k"
+	dossh -oStrictHostKeyChecking=yes -oHostKeyAlgorithms=$k,$all_algs
+	expect_nkeys $nkeys "learn hostkeys $k"
+	check_key_present $k || fail "didn't learn $k"
+done
+
+# Change one hostkey (non primary) and relearn
+verbose "learn changed non-primary hostkey"
+mv $OBJ/hkr.ssh-rsa.pub $OBJ/hkr.ssh-rsa.pub.old
+rm -f $OBJ/hkr.ssh-rsa
+${SSHKEYGEN} -qt ssh-rsa -f $OBJ/hkr.ssh-rsa -N '' || fatal "ssh-keygen $k"
+dossh -oStrictHostKeyChecking=yes
+# Check that the key was replaced
+expect_nkeys $nkeys "learn hostkeys"
+check_key_present ssh-rsa $OBJ/hkr.ssh-rsa.pub.old && fail "old key present"
+check_key_present ssh-rsa || fail "didn't learn changed key"
+
+# Add new hostkey (primary type) to sshd and connect
+verbose "learn new primary hostkey"
+${SSHKEYGEN} -qt ssh-rsa -f $OBJ/hkr.ssh-rsa-new -N '' || fatal "ssh-keygen $k"
+( cat $OBJ/sshd_proxy.orig ; echo HostKey $OBJ/hkr.ssh-rsa-new ) \
+    > $OBJ/sshd_proxy
+# Check new hostkey added
+dossh -oStrictHostKeyChecking=yes -oHostKeyAlgorithms=ssh-rsa,$all_algs
+expect_nkeys `expr $nkeys + 1` "learn hostkeys"
+check_key_present ssh-rsa || fail "current key missing"
+check_key_present ssh-rsa $OBJ/hkr.ssh-rsa-new.pub || fail "new key missing"
+
+# Remove old hostkey (primary type) from sshd
+verbose "rotate primary hostkey"
+cp $OBJ/sshd_proxy.orig $OBJ/sshd_proxy
+mv $OBJ/hkr.ssh-rsa.pub $OBJ/hkr.ssh-rsa.pub.old
+mv $OBJ/hkr.ssh-rsa-new.pub $OBJ/hkr.ssh-rsa.pub
+mv $OBJ/hkr.ssh-rsa-new $OBJ/hkr.ssh-rsa
+# Check old hostkey removed
+dossh -oStrictHostKeyChecking=yes -oHostKeyAlgorithms=ssh-rsa,$all_algs
+expect_nkeys $nkeys "learn hostkeys"
+check_key_present ssh-rsa $OBJ/hkr.ssh-rsa.pub.old && fail "old key present"
+check_key_present ssh-rsa || fail "didn't learn changed key"
+
+# Connect again, forcing rotated key
+verbose "check rotate primary hostkey"
+dossh -oStrictHostKeyChecking=yes -oHostKeyAlgorithms=ssh-rsa
+expect_nkeys 1 "learn hostkeys"
+check_key_present ssh-rsa || fail "didn't learn changed key"
+
+#	$OpenBSD: hostkey-rotate.sh,v 1.1 2015/01/26 06:12:18 djm Exp $
+#	Placed in the Public Domain.
+
+tid="hostkey rotate"
+
+# Prepare hostkeys file with one key
+
+# Connect to sshd
+
+# Check that other keys learned
+
+# Change one hostkey (non primary)
+
+# Connect to sshd
+
+# Check that the key was replaced
+