diff --git a/gdiff-ig.cabal b/gdiff-ig.cabal
--- a/gdiff-ig.cabal
+++ b/gdiff-ig.cabal
@@ -1,7 +1,7 @@
 category:               Generics
 copyright:              (c) 2011 Universiteit Utrecht
 name:                   gdiff-ig
-version:                0.1
+version:                0.1.1
 license:                BSD3
 license-file:           LICENSE
 author:                 José Pedro Magalhães
diff --git a/src/Generics/Instant/GDiff.hs b/src/Generics/Instant/GDiff.hs
--- a/src/Generics/Instant/GDiff.hs
+++ b/src/Generics/Instant/GDiff.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE GADTs                #-}
 {-# LANGUAGE TypeOperators        #-}
+{-# LANGUAGE TypeSynonymInstances #-}
 {-# LANGUAGE FlexibleContexts     #-}
 {-# LANGUAGE ScopedTypeVariables  #-}
 {-# LANGUAGE MagicHash            #-}