diff --git a/MemoTrie.cabal b/MemoTrie.cabal
--- a/MemoTrie.cabal
+++ b/MemoTrie.cabal
@@ -1,5 +1,5 @@
 Name:                MemoTrie
-Version:             0.4
+Version:             0.4.1
 Cabal-Version:       >= 1.2
 Synopsis:            Trie-based memo functions
 Category:            Data
diff --git a/src/Data/MemoTrie.hs b/src/Data/MemoTrie.hs
--- a/src/Data/MemoTrie.hs
+++ b/src/Data/MemoTrie.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE GADTs, TypeFamilies, TypeOperators, ScopedTypeVariables #-}
-{-# OPTIONS_GHC -Wall -frewrite-rules #-}
+{-# OPTIONS_GHC -Wall -fenable-rewrite-rules #-}
 -- ScopedTypeVariables works around a 6.10 bug.  The forall keyword is
 -- supposed to be recognized in a RULES pragma.
 
@@ -13,7 +13,7 @@
 -- Stability   :  experimental
 -- 
 -- Trie-based memoizer
--- Adapted from sjanssen's paste: "a lazy trie" <http://hpaste.org/3839>.
+-- Adapted from sjanssen's paste: \"a lazy trie\" <http://hpaste.org/3839>.
 ----------------------------------------------------------------------
 
 module Data.MemoTrie
@@ -31,7 +31,6 @@
 -- import Control.Category
 -- import Control.Arrow
 
-
 -- | Mapping from all elements of @a@ to the results of some function
 class HasTrie a where
     -- | Representation of trie with domain type @a@
@@ -245,6 +244,11 @@
     data Int :->: a = IntTrie (Word :->: a)
     untrie (IntTrie t) n = untrie t (fromIntegral n)
     trie f = IntTrie (trie (f . fromIntegral . toInteger))
+
+instance HasTrie Integer where
+    data Integer :->: a = IntegerTrie (Word :->: a)
+    untrie (IntegerTrie t) n = untrie t (fromIntegral n)
+    trie f = IntegerTrie (trie (f . fromIntegral . toInteger))
 
 
 -- TODO: make these definitions more systematic.
diff --git a/wikipage.tw b/wikipage.tw
--- a/wikipage.tw
+++ b/wikipage.tw
@@ -2,17 +2,20 @@
 
 == Abstract ==
 
-'''MemoTrie''' is functional library for creating efficient memo functions, using [http://en.wikipedia.org/wiki/Trie trie]s.  It's based on some code I got from Spencer Janssen and uses type families.
+'''MemoTrie''' is functional library for creating efficient memo functions, using [http://en.wikipedia.org/wiki/Trie trie]s.  It's based on [http://hpaste.org/3839 some code] from Spencer Janssen and uses type families.
 
 Besides this wiki page, here are more ways to find out about MemoTrie:
-* Read [http://code.haskell.org/MemoTrie/doc/html/ the library documentation].
-* Get the code repository: '''<tt>darcs get http://code.haskell.org/MemoTrie</tt>'''.
-* Install from [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/MemoTrie Hackage].
-* See the [[MemoTrie/Versions| version history]].
+* Visit the [http://hackage.haskell.org/cgi-bin/hackage-scripts/package/MemoTrie Hackage page] for library documentation and to download & install.
+* Or install with <tt>cabal install MemoTrie</tt>.
+* Get the code repository: <tt>darcs get http://code.haskell.org/MemoTrie</tt>.
+<!-- * See the [[MemoTrie/Versions| version history]]. -->
 
 Please leave comments at the [[Talk:MemoTrie|Talk page]].
 
 == See also ==
 
 * [http://www.haskell.org/haskellwiki/GHC/Indexed_types#An_associated_data_type_example An associated data type example]
-* [http://citeseer.ist.psu.edu/233124.html Generalizing Generalized Tries]
+* Ralf Hinze's ''[http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.223 Generalizing Generalized Tries]''
+* Related [http://conal.net/blog/tag/tries/ blog posts].
+* Use of MemoTrie in [[vector-space]].
+