diff --git a/doc/requirements.txt b/doc/requirements.txt
index a09abef7bb..7d36604765 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -5,5 +5,5 @@
 doc8>=0.6.0 # Apache-2.0
 openstackdocstheme>=1.19.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
diff --git a/requirements.txt b/requirements.txt
index d4ef17487a..9159f31196 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,7 +4,7 @@
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 docker>=2.4.2 # Apache-2.0
 Jinja2>=2.8 # BSD License (3 clause)
-GitPython>=1.0.1;python_version>='3.0' # BSD License (3 clause)
+GitPython>=1.0.1 # BSD License (3 clause)
 oslo.config>=5.1.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 setuptools!=24.0.0,!=34.0.0,!=34.0.1,!=34.0.2,!=34.0.3,!=34.1.0,!=34.1.1,!=34.2.0,!=34.3.0,!=34.3.1,!=34.3.2,!=36.2.0,>=21.0 # PSF/ZPL
diff --git a/tox.ini b/tox.ini
index 8510c58cf6..09b93e82a1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,7 +1,8 @@
 [tox]
-minversion = 2.5.0
+minversion = 3.1
 skipsdist = True
 envlist = pep8,py37,pypy
+ignore_basepython_conflict = True
 
 [testenv]
 basepython = python3