diff --git a/requirements_dev.txt b/requirements_dev.txt
index ea164a7f..7dc92041 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -3,7 +3,7 @@ bumpversion==0.5.3
 wheel==0.31.1
 watchdog==0.8.3
 flake8==3.5.0
-tox==2.9.1
+tox==4.23.0
 coverage==4.5.1
 Sphinx==1.7.7
 cryptography==2.3.1