diff --git a/tox.ini b/tox.ini
index 9ca919d..67c74c9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,6 @@
 skipsdist = True
 
 [testenv]
-basepython = python3
 usedevelop = True
 install_command = pip install {opts} {packages}
 setenv =
@@ -20,11 +19,13 @@
 basepython = python2.7
 
 [testenv:pep8]
+basepython = python3
 commands =
   flake8
   bandit -r castellan -x tests -s B105,B106,B107,B607
 
 [testenv:bandit]
+basepython = python3
 # This command runs the bandit security linter against the castellan
 # codebase minus the tests directory. Some tests are being excluded to
 # reduce the number of positives before a team inspection, and to ensure a
@@ -37,20 +38,25 @@
   bandit -r castellan -x tests -s B105,B106,B107,B607
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:cover]
+basepython = python3
 commands =
    python setup.py testr --coverage --testr-args='{posargs}'
    coverage report
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:releasenotes]
+basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:functional]
@@ -72,6 +78,7 @@
     {toxinidir}/tools/setup-vault-env.sh pifpaf -e VAULT_TEST run vault -- python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:genconfig]
+basepython = python3
 commands =
     oslo-config-generator --config-file=etc/castellan/functional-config-generator.conf
     oslo-config-generator --config-file=etc/castellan/sample-config-generator.conf
@@ -87,6 +94,7 @@
 import_exceptions = castellan.i18n
 
 [testenv:lower-constraints]
+basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt