diff --git a/tox.ini b/tox.ini
index d289c774bf..841cfa865d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,20 +1,20 @@
 [tox]
-minversion = 2.0
+minversion = 3.1
 envlist = docs
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 install_command = pip install -U {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
 deps = -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
 passenv = *_proxy *_PROXY
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
   bash -c "rm -rf doc/build"