diff --git a/requirements/dev.txt b/requirements/dev.txt
index 182a70a..2d307b7 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -5,7 +5,7 @@ bumpversion==0.5.3
 wheel==0.30.0
 watchdog==0.8.3
 flake8==3.5.0
-tox==2.9.1
+tox==4.23.0
 coverage==4.5.1
 Sphinx==1.7.0
 cryptography==2.1.4