diff --git a/tox.ini b/tox.ini
index 670709aa1..f56865819 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,8 +24,8 @@ deps=pytest-xdist
     mock
     nose
 commands=
-  py.test -n3 -rfsxX \
-        --junitxml={envlogdir}/junit-{envname}.xml testing
+  py.test -n1 -rfsxX \
+        --junitxml={envlogdir}/junit-{envname}.xml {posargs:testing}
 
 [testenv:py33-xdist]
 changedir=.