diff --git a/requirements.txt b/requirements.txt
--- a/requirements.txt
+++ b/requirements.txt
@@ -34,3 +34,5 @@ klein==15.3.1
 git+http://github.com/drewp/scales.git@448d59fb491b7631877528e7695a93553bfaaa93#egg=scales
 colormath==2.1.1
 noise==1.2.2
+
+typing==3.6.1