diff --git a/tox.ini b/tox.ini
index d7ae05a..a328659 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 2.0
+minversion = 2.5.0
 envlist = py37,py36,py27,pep8,docs
 
 [testenv]