diff --git a/tox.ini b/tox.ini
index 1ba93ca8f0..6650dad07e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,7 +18,7 @@ setenv = VIRTUAL_ENV={envdir}
 deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
-commands = nosetests test/unit {posargs}
+commands = nosetests {posargs:test/unit}
 
 [testenv:cover]
 setenv = VIRTUAL_ENV={envdir}