diff --git a/requirements_dev.txt b/requirements_dev.txt
index 02fe5e2..19b4de5 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -3,7 +3,7 @@ bumpversion==0.5.3
 wheel==0.29.0
 watchdog==0.8.3
 flake8==3.0.4
-tox==2.4.1
+tox==3.13.2
 coverage==4.2
 Sphinx==1.4.8
 cryptography==2.0.2