diff --git a/tox.ini b/tox.ini
index 00dd3b8..c4e4257 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@
 
 # documentation only
 [tox]
-minversion = 2.0
+minversion = 4.0
 envlist =
     docs,
     docs-linkcheck,