diff --git a/tools/test/stress2/misc/unionfs4.sh b/tools/test/stress2/misc/unionfs4.sh
index 2355005c1f8b..15ff314a980b 100755
--- a/tools/test/stress2/misc/unionfs4.sh
+++ b/tools/test/stress2/misc/unionfs4.sh
@@ -1,80 +1,82 @@
 #!/bin/sh
 
 #
 # SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 #
 # Copyright (c) 2021 Peter Holm
 #
 # 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.
 #
 
 # "mkdir: mkdir(d2), level 2. mkdir.c:96: No such file or directory" seen
 # with a non debug kernel.
 
 [ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
 . ../default.cfg
 
 # unionfs usage example from the man page:
 #	   mount -t cd9660 -o ro /dev/cd0 /usr/src
 #	   mount -t unionfs -o noatime /var/obj	/usr/src
 
 md1=$mdstart
 md2=$((md1 + 1))
 mp1=/mnt$md1
 mp2=/mnt$md2
 mkdir -p $mp1 $mp2
 set -e
 for i in $mp1 $mp2; do
 	mount | grep -q "on $i " && umount -f $i
 done
 for i in $md1 $md2; do
 	mdconfig -l | grep -q md$i && mdconfig -d -u $i
 done
 
 mdconfig -a -t swap -s 2g -u $md1
 mdconfig -a -t swap -s 2g -u $md2
+[ "$newfs_flags" = "-U" ] &&
+    newfs_flags="-j"	# "out of inodes" work around
 newfs $newfs_flags -n md$md1 > /dev/null
 newfs $newfs_flags -n md$md2 > /dev/null
 mount /dev/md$md1 $mp1
 mount /dev/md$md2 $mp2
 
 mount -t unionfs -o noatime $mp1 $mp2
 set +e
 mount | grep -E "$mp1|$mp2"
 
 export RUNDIR=$mp2/stressX
 export runRUNTIME=2m 
 
 (cd ..; ./run.sh marcus.cfg)
 
 ../tools/killall.sh
 while mount | grep -Eq "on $mp2 .*unionfs"; do
 	umount $mp2 && break
 	sleep 5
 done
 umount $mp2
 n=`find $mp1/stressX | wc -l`
 [ $n -eq 1 ] && s=0 || { find $mp1/stressX -ls | head -12; s=1; }
 umount $mp1
 mdconfig -d -u $md2
 mdconfig -d -u $md1
 exit $s