diff --git a/requirements.txt b/requirements.txt
index 5e553aa2..0ba05a55 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 py>=1.5.0
-tox==3.16.1
+tox==3.18.1
 pluggy==0.13.1
 pytest==4.6.1
 pytest-cov==2.10.0