diff --git a/tox.ini b/tox.ini
index d40d5b90..7bbbd0d5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,7 @@ envlist = py27, py37, pypy
 
 
 [testenv]
+# pyOpenSSL only needed for Python 2.7
 deps =
     mock
     pytest