diff --git a/tox.ini b/tox.ini
index 9098a48794..dac6fe36df 100644
--- a/tox.ini
+++ b/tox.ini
@@ -38,7 +38,7 @@ commands =
 [testenv:fail_fast_test_main]
 commands = 
     python3 -m pip install .
-    python3 -m unittest -ff locust.test.test_main
+    python3 -m unittest -f locust.test.test_main
 
 [testenv:black]
 deps = black==23.10.1