diff --git a/tox.ini b/tox.ini
index 1f89a76b..69ccf129 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,10 +25,12 @@ commands =
 # mode. To do this define the TRACE_FAILONLY environmental variable.
 
 [testenv:pep8]
+basepython = python3
 commands =
   flake8 {posargs}
 
 [testenv:cover]
+basepython = python3
 # Also do not run test_coverage_ext tests while gathering coverage as those
 # tests conflict with coverage.
 setenv =
@@ -42,14 +44,17 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands =
   python setup.py build_sphinx
   bash -c '! find doc/ -type f -name *.json | xargs -t -n1 python -m json.tool 2>&1 > /dev/null | grep -B1 -v ^python'
 
 [testenv:releasenotes]
+basepython = python3
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
@@ -73,6 +78,7 @@ enable-extensions = H904
 local-check-factory = compute_hyperv.hacking.checks.factory
 
 [testenv:pip-missing-reqs]
+basepython = python3
 # do not install test-requirements as that will pollute the virtualenv for
 # determining missing packages
 # this also means that pip-missing-reqs must be installed separately, outside