diff --git a/tox.ini b/tox.ini
index 328da2e..6ca7aac 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,9 +13,11 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
+basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]