diff --git a/tests/test_run.py b/tests/test_run.py
index 5a2dc09a..bc47df4d 100644
--- a/tests/test_run.py
+++ b/tests/test_run.py
@@ -83,5 +83,5 @@ def test_run_windows(exec, workers, docker, wsl, cmd):
     ],
 )
 def test_run_unix(exec, workers, docker, cmd):
-    cmd.replace("PLACEHOLDER", f"-e LOCAL_USER_ID={os.getuid()}")
+    cmd = cmd.replace("PLACEHOLDER", f"-e LOCAL_USER_ID={os.getuid()}")
     test_run(exec, workers, docker, False, cmd)