diff --git a/tox.ini b/tox.ini
index 7c3fa3f9..d19cf071 100644
--- a/tox.ini
+++ b/tox.ini
@@ -42,6 +42,7 @@ commands = flake8 {posargs} hooks unit_tests tests actions lib
            charm-proof
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:func]