diff --git a/requirements_dev.txt b/requirements_dev.txt
index 56e4545..a67119b 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -3,7 +3,7 @@ bumpversion==0.5.3
 wheel==0.32.2
 watchdog==0.9.0
 flake8==3.6.0
-tox==3.5.2
+tox==3.8.5
 coverage==4.5.1
 Sphinx==1.8.2
 twine==1.12.1