diff --git a/tox.ini b/tox.ini
index 4966d8bf4..9beff2542 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,7 +23,7 @@ commands =
     nocov: pytest {posargs}
 
 [testenv:htmlcov]
-basepython = {env:TOXPYTHON:python3.5}
+basepython = {env:TOXPYTHON:python3.6}
 deps =
     coverage>=4.3
 skip_install = true
@@ -44,7 +44,7 @@ commands =
     codecov --env TOXENV
 
 [testenv:bdist]
-basepython = {env:TOXPYTHON:python3.5}
+basepython = {env:TOXPYTHON:python3.6}
 deps =
     setuptools
     wheel