diff --git a/usr.bin/renice/tests/renice_test.sh b/usr.bin/renice/tests/renice_test.sh
index 323fe44591c8..9321e0f327ae 100644
--- a/usr.bin/renice/tests/renice_test.sh
+++ b/usr.bin/renice/tests/renice_test.sh
@@ -1,169 +1,169 @@
 #!/bin/sh
 #-
 # Copyright (c) 2022 Klara, Inc.
 # All rights reserved.
 #
 # 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.
 #
 
 # Name of user to use for -u tests when running as root.  Beware that
 # processes owned by that user will be affected by the test.
 TEST_USER=nobody
 
 _renice() {
 	atf_check -o empty -e ignore -s exit:0 renice "$@"
 }
 
 # Set a process's nice number to an absolute value
 atf_test_case renice_abs_pid
 renice_abs_pid_body() {
 	local pid nice incr
 	sleep 60 &
 	pid=$!
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice $((nice+incr)) $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Change a process's nice number by a relative value
 atf_test_case renice_rel_pid
 renice_rel_pid_body() {
 	local pid nice incr
 	sleep 60 &
 	pid=$!
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice -n $incr $pid
 	_renice -p -n $incr $pid
 	_renice -n $incr -p $pid
 	atf_check_equal $((nice+incr+incr+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Set a process group's nice number to an absolute value
 atf_test_case renice_abs_pgid
 renice_abs_pgid_body() {
 	local pid pgid nice incr
 	# make sure target runs in a different pgrp than ours
 	pid=$(sh -mc "sleep 60 >/dev/null & echo \$!")
 	pgid="$(ps -o pgid= -p $pid)"
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice $((nice+incr)) -g $pgid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Change a process group's nice number by a relative value
 atf_test_case renice_rel_pgid
 renice_rel_pgid_body() {
 	local pid pgid nice incr
 	# make sure target runs in a different pgrp than ours
 	pid=$(sh -mc "sleep 60 >/dev/null & echo \$!")
 	pgid="$(ps -o pgid= -p $pid)"
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice -g -n $incr $pgid
 	_renice -n $incr -g $pgid
 	atf_check_equal $((nice+incr+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Set a user's processes' nice numbers to an absolute value
 atf_test_case renice_abs_user
 renice_abs_user_head() {
 	atf_set "require.user" "root"
 }
 renice_abs_user_body() {
 	local user pid nice incr
-	pid=$(su -m $TEST_USER -c "sleep 60 >/dev/null & echo \$!")
+	pid=$(su -m $TEST_USER -c "/bin/sh -c 'sleep 60 >/dev/null & echo \$!'")
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice $((nice+incr)) -u $TEST_USER
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Change a user's processes' nice numbers by a relative value
 atf_test_case renice_rel_user
 renice_rel_user_head() {
 	atf_set "require.user" "root"
 }
 renice_rel_user_body() {
 	local user pid nice incr
-	pid=$(su -m $TEST_USER -c "sleep 60 >/dev/null & echo \$!")
+	pid=$(su -m $TEST_USER -c "/bin/sh -c 'sleep 60 >/dev/null & echo \$!'")
 	nice="$(ps -o nice= -p $pid)"
 	incr=3
 	_renice -u -n $incr $TEST_USER
 	_renice -n $incr -u $TEST_USER
 	atf_check_equal $((nice+incr+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 # Test various delimiter positions
 atf_test_case renice_delim
 renice_delim_body() {
 	local pid nice incr
 	sleep 60 &
 	pid=$!
 	nice="$(ps -o nice= -p $pid)"
 	incr=0
 	# without -p
 	: $((incr=incr+1))
 	_renice -- $((nice+incr)) $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice $((nice+incr)) -- $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice $((nice+incr)) $pid --
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	# with -p
 	: $((incr=incr+1))
 	_renice -p -- $((nice+incr)) $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice -p $((nice+incr)) -- $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice -p $((nice+incr)) $pid --
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice $((nice+incr)) -p -- $pid
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	: $((incr=incr+1))
 	_renice $((nice+incr)) -p $pid --
 	atf_check_equal $((nice+incr)) "$(ps -o nice= -p $pid)"
 	kill $pid
 }
 
 atf_init_test_cases() {
 	atf_add_test_case renice_abs_pid
 	atf_add_test_case renice_rel_pid
 	atf_add_test_case renice_abs_pgid
 	atf_add_test_case renice_rel_pgid
 	atf_add_test_case renice_abs_user
 	atf_add_test_case renice_rel_user
 	atf_add_test_case renice_delim
 }