diff --git a/tox.ini b/tox.ini
index 74310da..dd9a622 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,6 +11,7 @@ install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:deploy-guide]