diff --git a/tox.ini b/tox.ini
index 98e14b2fd31..ab89fb5c0a6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,6 +25,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands =
   find . -type f -name "*.pyc" -delete
   stestr run '{posargs}'
+  stestr slowest
 
 whitelist_externals =
   bash