diff --git a/tox.ini b/tox.ini
index ff81da8c5..fe25b9350 100644
--- a/tox.ini
+++ b/tox.ini
@@ -18,35 +18,42 @@ commands =
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
+basepython = python3
 commands =
     doc8 doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
     flake8
     bandit -r watcher -x tests -n5 -ll -s B320
 
 [testenv:venv]
+basepython = python3
 setenv = PYTHONHASHSEED=0
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 commands =
     python setup.py testr --coverage --testr-args='{posargs}'
     coverage report
 
 [testenv:docs]
+basepython = python3
 setenv = PYTHONHASHSEED=0
 commands =
     doc8 doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
     python setup.py build_sphinx
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper -t watcher/tests {posargs}
 
 [testenv:genconfig]
+basepython = python3
 sitepackages = False
 commands =
     oslo-config-generator --config-file etc/watcher/oslo-config-generator/watcher.conf
 
 [testenv:genpolicy]
+basepython = python3
 commands =
     oslopolicy-sample-generator --config-file etc/watcher/oslo-policy-generator/watcher-policy-generator.conf
 
@@ -59,6 +66,7 @@ enable-extensions = H106,H203,H904
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,*sqlalchemy/alembic/versions/*,demo/,releasenotes
 
 [testenv:wheel]
+basepython = python3
 commands = python setup.py bdist_wheel
 
 [hacking]
@@ -71,9 +79,11 @@ extension=.rst
 ignore-path=doc/source/image_src,doc/source/man,doc/source/api
 
 [testenv:releasenotes]
+basepython = python3
 commands = sphinx-build -a -W -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:bandit]
+basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -r watcher -x tests -n5 -ll -s B320