diff --git a/servant-iCalendar.cabal b/servant-iCalendar.cabal
--- a/servant-iCalendar.cabal
+++ b/servant-iCalendar.cabal
@@ -1,5 +1,5 @@
 name:           servant-iCalendar
-version:        0.1.0.0
+version:        0.1.0.1
 synopsis:       Servant support for iCalendar
 description:    Servant support for iCalendar
 category:       Web
diff --git a/src/Servant/ICalendar.hs b/src/Servant/ICalendar.hs
--- a/src/Servant/ICalendar.hs
+++ b/src/Servant/ICalendar.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE DeriveDataTypeable #-}
 -- |
 -- Module      :  Servant.ICalendar
 -- License     :  BSD-3-Clause