diff --git a/tox.ini b/tox.ini
index 46dddea7..fb6ff5ea 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,9 @@ commands =
     doc8 priorities/ specs/ doc/source README.rst
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands = sphinx-build -W -b html doc/source doc/build/html