diff --git a/tox.ini b/tox.ini
index dc7bc53..91cbd21 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,16 +11,20 @@ commands =
   python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
+basepython = python3
 commands = flake8 {posargs}
 
 [testenv:cover]
+basepython = python3
 commands =
   python setup.py testr --coverage
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]