diff --git a/test/testsuite-16.units/extend-timeout.sh b/test/testsuite-16.units/extend-timeout.sh
index 40bf046dcd..ed1af8afeb 100755
--- a/test/testsuite-16.units/extend-timeout.sh
+++ b/test/testsuite-16.units/extend-timeout.sh
@@ -4,23 +4,15 @@ set -e
 set -o pipefail
 
 # sleep interval (seconds)
-sleep_interval=1
+: ${sleep_interval:=1}
 # extend_timeout_interval second(s)
-extend_timeout_interval=1
+: ${extend_timeout_interval:=1}
 # number of sleep_intervals before READY=1
-start_intervals=10
+: ${start_intervals:=10}
 # number of sleep_intervals before exiting
-stop_intervals=10
+: ${stop_intervals:=10}
 # run intervals, number of sleep_intervals to run
-run_intervals=7
-# service name
-SERVICE=unknown
-
-while [ $# -gt 0 ];
-do
-    eval ${1%=*}=${1#*=}
-    shift
-done
+: ${run_intervals:=7}
 
 # We convert to usec
 extend_timeout_interval=$(( $extend_timeout_interval * 1000000 ))
diff --git a/test/testsuite-16.units/fail-runtime.service b/test/testsuite-16.units/fail-runtime.service
index 06417f7133..baa655f2f1 100644
--- a/test/testsuite-16.units/fail-runtime.service
+++ b/test/testsuite-16.units/fail-runtime.service
@@ -8,4 +8,5 @@ Type=notify
 TimeoutStartSec=4
 TimeoutStopSec=4
 RuntimeMaxSec=10
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=fail_runtime extend_timeout_interval=5 sleep_interval=7 start_intervals=0 run_intervals=2 stop_intervals=0
+Environment=SERVICE=fail_runtime extend_timeout_interval=5 sleep_interval=7 start_intervals=0 run_intervals=2 stop_intervals=0
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
diff --git a/test/testsuite-16.units/fail-start.service b/test/testsuite-16.units/fail-start.service
index 95e9b01d12..882900440f 100644
--- a/test/testsuite-16.units/fail-start.service
+++ b/test/testsuite-16.units/fail-start.service
@@ -9,4 +9,5 @@ Type=notify
 TimeoutStartSec=10
 TimeoutStopSec=4
 RuntimeMaxSec=4
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=fail_start extend_timeout_interval=5 sleep_interval=7 start_intervals=2 run_intervals=0 stop_intervals=0
+Environment=SERVICE=fail_start extend_timeout_interval=5 sleep_interval=7 start_intervals=2 run_intervals=0 stop_intervals=0
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
diff --git a/test/testsuite-16.units/fail-stop.service b/test/testsuite-16.units/fail-stop.service
index 7fc66003a4..cdea2a9a2d 100644
--- a/test/testsuite-16.units/fail-stop.service
+++ b/test/testsuite-16.units/fail-stop.service
@@ -8,7 +8,8 @@ Type=notify
 TimeoutStartSec=4
 TimeoutStopSec=10
 RuntimeMaxSec=4
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=fail_stop extend_timeout_interval=5 sleep_interval=7 start_intervals=0 run_intervals=0 stop_intervals=2
+Environment=SERVICE=fail_stop extend_timeout_interval=5 sleep_interval=7 start_intervals=0 run_intervals=0 stop_intervals=2
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
 # Due to 6041a7ee2c1bbff6301082f192fc1b0882400d42 SIGTERM isn't sent as the service shuts down with STOPPING=1
 # This file makes the test assess.sh quicker by notifing it that this test has finished.
 ExecStopPost=/bin/bash -c '[[ $SERVICE_RESULT == timeout && $EXIT_CODE == killed ]] && touch /fail_runtime.terminated'
diff --git a/test/testsuite-16.units/success-all.service b/test/testsuite-16.units/success-all.service
index c30ee78dfa..e2d7e607ba 100644
--- a/test/testsuite-16.units/success-all.service
+++ b/test/testsuite-16.units/success-all.service
@@ -10,4 +10,5 @@ Type=notify
 TimeoutStartSec=4
 TimeoutStopSec=4
 RuntimeMaxSec=4
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=success_all extend_timeout_interval=4 sleep_interval=2 start_intervals=3 run_intervals=3 stop_intervals=3
+Environment=SERVICE=success_all extend_timeout_interval=4 sleep_interval=2 start_intervals=3 run_intervals=3 stop_intervals=3
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
diff --git a/test/testsuite-16.units/success-runtime.service b/test/testsuite-16.units/success-runtime.service
index 8f83cdb4a1..15283b73a8 100644
--- a/test/testsuite-16.units/success-runtime.service
+++ b/test/testsuite-16.units/success-runtime.service
@@ -9,4 +9,5 @@ Type=notify
 TimeoutStartSec=4
 TimeoutStopSec=4
 RuntimeMaxSec=8
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=success_runtime extend_timeout_interval=4 sleep_interval=6 start_intervals=0 run_intervals=1 stop_intervals=0
+Environment=SERVICE=success_runtime extend_timeout_interval=4 sleep_interval=6 start_intervals=0 run_intervals=1 stop_intervals=0
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
diff --git a/test/testsuite-16.units/success-start.service b/test/testsuite-16.units/success-start.service
index 26c74390c0..cfdcc33cc8 100644
--- a/test/testsuite-16.units/success-start.service
+++ b/test/testsuite-16.units/success-start.service
@@ -8,4 +8,5 @@ Type=notify
 TimeoutStartSec=8
 TimeoutStopSec=4
 RuntimeMaxSec=4
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=success_start extend_timeout_interval=4 sleep_interval=6 start_intervals=1 run_intervals=0 stop_intervals=0
+Environment=SERVICE=success_start extend_timeout_interval=4 sleep_interval=6 start_intervals=1 run_intervals=0 stop_intervals=0
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh
diff --git a/test/testsuite-16.units/success-stop.service b/test/testsuite-16.units/success-stop.service
index b20908ad75..c4600ace41 100644
--- a/test/testsuite-16.units/success-stop.service
+++ b/test/testsuite-16.units/success-stop.service
@@ -8,4 +8,5 @@ Type=notify
 TimeoutStartSec=4
 TimeoutStopSec=8
 RuntimeMaxSec=4
-ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh SERVICE=success_stop extend_timeout_interval=4 sleep_interval=6 start_intervals=0 run_intervals=0 stop_intervals=1
+Environment=SERVICE=success_stop extend_timeout_interval=4 sleep_interval=6 start_intervals=0 run_intervals=0 stop_intervals=1
+ExecStart=/usr/lib/systemd/tests/testdata/testsuite-16.units/extend-timeout.sh