diff --git a/tox.ini b/tox.ini
index 175a7cd..75acf02 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,6 +39,7 @@ commands =
   stestr run --serial {posargs}
 
 [testenv:pep8]
+basepython = python3
 commands =
   flake8
   python setup.py check --restructuredtext --strict
@@ -48,9 +49,11 @@ commands =
   python setup.py build_sphinx
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 # Also do not run test_coverage_ext tests while gathering coverage as those
 # tests conflict with coverage.
 setenv =