diff --git a/requirements_dev.txt b/requirements_dev.txt
index d477a77..0fec0fa 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==3.2.1
-tox==2.5.0
+tox==3.5.0
 coverage==4.2
 pytest-aiohttp==0.1.3
 Sphinx==1.5