diff --git a/tox.ini b/tox.ini
index 32b2c68..124d9e7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -35,6 +35,7 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = flake8 {posargs} charms_openstack unit_tests
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]