diff --git a/tox.ini b/tox.ini
index f883e86c..cd8c8ac6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -31,13 +31,16 @@ commands =
   coverage xml -o cover/coverage.xml
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:releasenotes]
+basepython = python3
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [flake8]