diff --git a/tox.ini b/tox.ini
index 2876ddeffe..0c6a751edf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@ env_list = unitest,type,dictionaries
 [testenv:unitest]
 description = run unit tests
 extras = dev
-commands = pytest --cov=codespell_lib codespell_lib
+commands = pytest --cov=codespell_lib {posargs} codespell_lib
 
 [testenv:type]
 description = run type checks