diff --git a/requirements.txt b/requirements.txt
index 43ae289..9775fa2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -27,7 +27,7 @@ six==1.2.0
 transaction==1.4.0
 translationstring==1.1
 venusian==1.0a7
-waitress==1.4.3
+waitress==2.1.1
 wsgiref==0.1.2
 zope.deprecation==4.0.2
 zope.interface==4.0.3