diff --git a/requirements_dev.txt b/requirements_dev.txt
index a0e4efca..684cf64e 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -3,7 +3,7 @@ bump2version==0.5.8
 wheel==0.31.1
 watchdog==0.8.3
 flake8==3.5.0
-tox==3.1.2
+tox==3.2.1
 coverage==4.5.1
 Sphinx==1.7.6
 # only used for setup script