diff --git a/tox.ini b/tox.ini
index 4bdbc6d0..2981a782 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,6 +3,7 @@ minversion = 2.0
 envlist = py35,py27,pypy,pep8,bandit
 
 [testenv]
+basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     BRANCH_NAME=master
@@ -27,6 +28,7 @@ commands =
     find . -type f -name "*.py[co]" -delete
     python setup.py testr --slowest --testr-args='{posargs}'
     doc8 --ignore-path "doc/source/history.rst" doc/source
+basepython = python2.7
 
 [testenv:venv]
 commands = {posargs}