diff --git a/tox.ini b/tox.ini
index fa2a2da1..57bcd788 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,6 +25,12 @@ commands = flake8 {posargs}
 basepython = python3
 commands = {posargs}
 
+[testenv:py3-dev]
+basepython = python3
+commands =
+  pip install {env:HORIZON_REPO:git+git://git.openstack.org/openstack/horizon}
+  {[testenv]commands}
+
 [testenv:cover]
 basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'