diff --git a/tox.ini b/tox.ini
index c78ad6c..9415b1c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6
-envlist = py27,pypy,pep8
+envlist = py27,py35,pypy,pep8
 skipsdist = True
 
 [testenv]
@@ -16,21 +16,27 @@ commands = python setup.py test --slowest --testr-args='{posargs}'
 commands = flake8
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:genconfig]
+basepython = python3
 commands = oslo-config-generator --config-file etc/cloudpulse/cloudpulse-config-generator.conf
 
 [testenv:cover]
+basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:bandit]
+basepython = python3
 deps = bandit
 commands = bandit -c bandit.yaml -r cloudpulse -p gate