diff --git a/tox.ini b/tox.ini
index 88f46ad..b3629e8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,9 +12,11 @@ deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:spelling]