diff --git a/test/test-functions b/test/test-functions
index 359eb90314..1c0441e7c5 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -538,6 +538,7 @@ run_nspawn() {
         "--kill-signal=SIGKILL"
         "--directory=${1:?}"
         "--setenv=SYSTEMD_UNIT_PATH=/usr/lib/systemd/tests/testdata/testsuite-$2.units:/usr/lib/systemd/tests/testdata/units:"
+        "--machine=TEST-$TESTID"
     )
     local kernel_params=(
         "$PATH_TO_INIT"