diff --git a/tox.ini b/tox.ini
index a25ad51..6f52fd2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,6 +23,7 @@ commands = stestr run {posargs}
            stestr slowest
 
 [testenv:pep8]
+basepython = python3
 usedevelop = False
 skip_install = True
 deps =
@@ -37,9 +38,11 @@ commands =
     flake8 os_client_config
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source os_client_config --parallel-mode
@@ -50,6 +53,7 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+basepython = python3
 skip_install = True
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
@@ -59,6 +63,7 @@ commands =
   sphinx-build -W -d doc/build/doctrees -b html doc/source/ doc/build/html
 
 [testenv:releasenotes]
+basepython = python3
 skip_install = True
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}