diff --git a/requirements_dev.txt b/requirements_dev.txt
index d131deb..40dd504 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -4,7 +4,7 @@ wheel==0.29.0
 watchdog==0.8.3
 flake8==3.3.0
 flake8-docstrings==1.0.3
-tox==2.6.0
+tox==3.15.2
 coverage==4.3.4
 Sphinx==1.5.3
 cryptography==1.7.2