diff --git a/tox.ini b/tox.ini
index d26fe54..2ade39b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -26,7 +26,7 @@ commands = {posargs}
 
 [testenv:cover]
 basepython = python3
-commands = python setup.py test --coverage --testr-args='{posargs}'
+commands = python setup.py test --coverage --testr-args={posargs}
 
 [testenv:docs]
 basepython = python3