diff --git a/tox.ini b/tox.ini
index b550330..b006137 100644
--- a/tox.ini
+++ b/tox.ini
@@ -33,6 +33,7 @@ setenv =
 
 
 [testenv:docs]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands=
     bash -c "rm -rf doc/build"
@@ -46,6 +47,7 @@ extensions = .rst
 
 
 [testenv:releasenotes]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
     sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
@@ -53,6 +55,7 @@ commands =
 
 # environment used by the -infra templated docs job
 [testenv:venv]
+basepython = python3
 commands =
     {posargs}
 
@@ -65,6 +68,7 @@ commands =
 
 
 [testenv:pep8]
+basepython = python3
 commands =
     {[testenv:tests_clone]commands}
     bash -c "{toxinidir}/tests/common/test-pep8.sh"