diff --git a/tox.ini b/tox.ini
index f5dbbf1c..5cd30838 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,8 +7,7 @@ setenv = LANG=en_US.UTF-8
          LC_ALL=C
 deps= -r{toxinidir}/test-requirements.txt
 commands=
-    bash -c 'if [ ! -d ./.testrepository ] ; then testr init ; fi'
-    bash -c 'testr run --parallel {posargs} ; RET=$?; echo "Slowest Tests" ; testr slowest && exit $RET'
+    python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
 commands =