diff --git a/tox.ini b/tox.ini
index 4d54d9a..46b2463 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,20 +19,25 @@ commands = ostestr {posargs}
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
+basepython = python3
 commands =
     flake8 {posargs}
     doc8 README.rst CONTRIBUTING.rst HACKING.rst doc/source
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [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}
 
 [flake8]