diff --git a/setup.cfg b/setup.cfg
index 6d04000..a3d81b2 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -13,10 +13,9 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 
 [files]
 packages =
diff --git a/test-requirements.txt b/test-requirements.txt
index c7549fd..f4b6f8e 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -5,8 +5,7 @@
 hacking>=1.1.0,<1.2.0 # Apache-2.0
 
 # docs
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 # releasenotes
 reno>=2.5.0 # Apache-2.0
diff --git a/tox.ini b/tox.ini
index bc754d8..d051c4e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
-envlist = py35,py27,pypy,pep8
+minversion = 3.1.1
+envlist = py36,py37,pypy,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt} {opts} {packages}
 setenv =
@@ -16,15 +18,12 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = stestr run {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     PYTHON=coverage run --source blazar_tempest_plugin --parallel-mode
@@ -35,28 +34,23 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
-basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:pdf-docs]
-basepython = python3
 whitelist_externals = make
 commands =
     sphinx-build -b latex doc/source doc/build/pdf
     make -C doc/build/pdf
 
 [testenv:releasenotes]
-basepython = python3
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]
 # E123, E125 skipped as they are invalid PEP-8.
-
 show-source = True
 ignore = E123,E125
 builtins = _