diff --git a/tox.ini b/tox.ini
index 870dc59..3f55e7a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,6 +13,7 @@ deps =
   -r{toxinidir}/test-requirements.txt
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:checkbuild]