diff --git a/requirements.txt b/requirements.txt
index 7e8c2ff..f5bdd75 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 flake8==3.7.8
 pytest==4.6.3
 pytest-cov==2.7.1
-tox==3.14.0
+tox==3.20.1
 isort==4.3.18
 -e .