diff --git a/tox.ini b/tox.ini
index 50fe956..4a0ac5b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,7 +9,9 @@ deps = -r{toxinidir}/requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx