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
@@ -97,7 +97,7 @@ renice_abs_user_head() {
 }
 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 $TEST_USER
@@ -112,7 +112,7 @@ renice_rel_user_head() {
 }
 renice_rel_user_body() {
 	local user pid nice incr
-	pid=$(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