diff --git a/requirements_dev.txt b/requirements_dev.txt
index d6ad529..d189fcd 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -2,7 +2,7 @@ pip==9.0.1
 wheel==0.30.0
 watchdog==0.8.3
 flake8==3.4.1
-tox==2.9.1
+tox==3.7.0
 coverage==4.4.1
 Sphinx==1.6.3
 PyYAML==3.12