diff --git a/cndict.cabal b/cndict.cabal
--- a/cndict.cabal
+++ b/cndict.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                cndict
-version:             0.5.1
+version:             0.5.2
 synopsis:            Chinese/Mandarin <-> English dictionary, Chinese lexer.
 -- description:
 license:             PublicDomain
diff --git a/src/Data/Chinese/Pinyin.hs b/src/Data/Chinese/Pinyin.hs
--- a/src/Data/Chinese/Pinyin.hs
+++ b/src/Data/Chinese/Pinyin.hs
@@ -1,7 +1,8 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternGuards     #-}
 module Data.Chinese.Pinyin
-  ( toToneMarks
+  ( restoreUmlaut
+  , toToneMarks
   , fromToneMarks
   , clearToneMarks
   ) where