diff --git a/tox.ini b/tox.ini
index 570c029..714adec 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,8 +1,7 @@
 [tox]
-minversion = 3.1.1
+minversion = 3.18.0
 envlist = py36,pypy,pep8
 skipsdist = True
-ignore_basepython_conflict = True
 
 [testenv]
 usedevelop = True
@@ -13,7 +12,6 @@ deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'
-basepython = python3
 
 [testenv:pep8]
 commands = flake8 {posargs}