diff --git a/tox.ini b/tox.ini
index 8fcdadf..aede237 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,8 +9,10 @@ setenv = VIRTUAL_ENV={envdir}
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -b html doc/source doc/build/html