diff --git a/requirements_dev.txt b/requirements_dev.txt
index 9f400f4..8565a63 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -2,7 +2,7 @@ pip==9.0.1
 bumpversion==0.5.3
 wheel==0.30.0
 flake8==3.5.0
-tox==3.2.1
+tox==3.25.1
 coverage==4.5.1
 Sphinx==1.8.0
 pytest==3.8.0