diff --git a/tox.ini b/tox.ini
index 6d9541e3..a73f03d7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,6 +15,7 @@ deps = scrapy>=1.0.0
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
+basepython = python3
 commands =
     python setup.py check --restructuredtext --strict
     flake8
@@ -27,15 +28,18 @@ commands =
     bashate bin/doc-tools-check-languages
 
 [testenv:releasenotes]
+basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:sitemap]
 # commands = functional test command goes here
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:bindep]
@@ -45,6 +49,7 @@ commands = python setup.py build_sphinx
 # separately, outside of the requirements files, and develop mode disabled
 # explicitly to avoid unnecessarily installing the checked-out repo too (this
 # further relies on "tox.skipsdist = True" above).
+basepython = python3
 deps = bindep
 commands = bindep test
 usedevelop = False