diff --git a/tox.ini b/tox.ini
index e993671f..b8bb5745 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,9 +16,11 @@ whitelist_externals = bash
 downloadcache = ~/cache/pip
 
 [testenv:pep8]
+basepython = python3
 commands = flake8
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:py27]
@@ -26,6 +28,7 @@ commands =
     stestr run --black-regex ".tests.functional" '{posargs}'
 
 [testenv:py35]
+basepython = python3
 commands =
     stestr run --black-regex ".tests.functional" '{posargs}'
 
@@ -37,6 +40,7 @@ commands =
     stestr run --black-regex ".tests.unit" '{posargs}'
 
 [testenv:cover]
+basepython = python3
 commands =
   coverage erase
   python setup.py testr --coverage --testr-args='--concurrency=1 {posargs}'
@@ -44,9 +48,11 @@ commands =
   coverage html --include='os_vif/*' -d covhtml -i
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:releasenotes]
+basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [flake8]