diff --git a/tox.ini b/tox.ini
index 545df4f..fb1092b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,7 @@ minversion = 1.6
 skipsdist = True
 
 [testenv]
+basepython = python3
 setenv = VIRTUAL_ENV={envdir}
 usedevelop = True
 whitelist_externals = rm
@@ -15,6 +16,7 @@ commands =
    rm -f .testrepository/times.dbm
 
 [testenv:functional]
+basepython = python3
 setenv = OS_TEST_PATH=./apmec/tests/functional
 deps =
   {[testenv]deps}
@@ -36,6 +38,7 @@ deps =
 sitepackages = True
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:debug-py27]
@@ -56,6 +59,7 @@ commands =
 whitelist_externals = bash
 
 [testenv:i18n]
+basepython = python3
 commands = python ./tools/check_i18n.py ./apmec ./tools/i18n_cfg.py
 
 [testenv:docs]
@@ -65,6 +69,7 @@ commands =
     python setup.py build_sphinx
 
 [testenv:api-ref]
+basepython = python3
 # This environment is called from CI scripts to test and publish
 # the API Ref to developer.openstack.org.
 commands =
@@ -73,11 +78,12 @@ commands =
 whitelist_externals = rm
 
 [testenv:releasenotes]
+basepython = python3
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
-
 [testenv:cover]
+basepython = python3
 # Also do not run test_coverage_ext tests while gathering coverage as those
 # tests conflict with coverage.
 commands =
@@ -86,6 +92,7 @@ commands =
   coverage report
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]
@@ -101,10 +108,12 @@ import_exceptions = apmec._i18n
 local-check-factory = apmec.hacking.checks.factory
 
 [testenv:config-gen]
+basepython = python3
 commands =
     oslo-config-generator --config-file=etc/config-generator.conf
 
 [testenv:lower-constraints]
+basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt