diff --git a/nixos/lib/test-driver/test-driver.py b/nixos/lib/test-driver/test-driver.py
index 84661a4a758c..bf46d0df97f9 100644
--- a/nixos/lib/test-driver/test-driver.py
+++ b/nixos/lib/test-driver/test-driver.py
@@ -369,7 +369,7 @@ class Machine:
             q = q.replace("'", "\\'")
             return self.execute(
                 (
-                    "su -l {} -c "
+                    "su -l {} --shell /bin/sh -c "
                     "$'XDG_RUNTIME_DIR=/run/user/`id -u` "
                     "systemctl --user {}'"
                 ).format(user, q)