diff --git a/tox.ini b/tox.ini
index 63d2bd0..2c19948 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,5 +5,5 @@ envlist = py{27,34,35}-twisted-{old,new}
 [testenv]
 extras = tests
 deps =
-    twisted-old: twisted==16.0.0
+    twisted-old: twisted==17.0.0
 commands = python -m unittest discover