diff --git a/tox.ini b/tox.ini
index fd10c3a799..422f683b54 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,6 +22,7 @@ commands =
   bash tools/pretty_tox.sh '{posargs}'
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper -t magnum/tests/unit {posargs}
 
 [testenv:debug-py27]
@@ -110,6 +111,7 @@ commands =
   bash tools/pretty_tox.sh '{posargs}'
 
 [testenv:pep8]
+basepython = python3
 commands =
   doc8 -e .rst specs/ doc/source/ contrib/ CONTRIBUTING.rst HACKING.rst README.rst
   bash tools/flake8wrap.sh {posargs}
@@ -123,24 +125,30 @@ commands =
       -print0 | xargs -0 bashate -v -iE006,E010,E042 -eE005"
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:bandit]
+basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -r magnum -x tests -n5 -ll
 
 [testenv:cover]
+basepython = python3
 commands = {toxinidir}/tools/cover.sh {posargs}
 
 [testenv:docs]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:genconfig]
+basepython = python3
 commands =
     oslo-config-generator --config-file etc/magnum/magnum-config-generator.conf
 
 [testenv:genpolicy]
+basepython = python3
 commands =
     oslopolicy-sample-generator --config-file etc/magnum/magnum-policy-generator.conf
 
@@ -156,6 +164,7 @@ exclude = .venv,.git,.tox,dist,*lib/python*,*egg,build,tools,releasenotes
 local-check-factory = magnum.hacking.checks.factory
 
 [testenv:pip-check-reqs]
+basepython = python3
 # do not install test-requirements as that will pollute the virtualenv for
 # determining missing packages
 # this also means that pip_check_reqs must be installed separately, outside
@@ -165,15 +174,18 @@ deps = pip_check_reqs
 commands=pip-missing-reqs -d --ignore-file=magnum/tests/* magnum
 
 [testenv:releasenotes]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:install-guide]
+basepython = python3
 commands = sphinx-build -a -E -W -d install-guide/build/doctrees -b html install-guide/source install-guide/build/html
 
 [testenv:api-ref]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf api-ref/build
@@ -189,6 +201,7 @@ deps =
 # This environment can be used to quickly validate that all needed system
 # packages required to successfully execute test targets are installed
 [testenv:bindep]
+basepython = python3
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed