diff --git a/Data/IntMap/CharMap.hs b/Data/IntMap/CharMap.hs
--- a/Data/IntMap/CharMap.hs
+++ b/Data/IntMap/CharMap.hs
@@ -45,7 +45,7 @@
 notMember :: Key -> CharMap a -> Bool
 notMember k (CharMap m) = M.notMember (C.ord k) m
 
-lookup :: Monad m => Key -> CharMap a -> m a
+lookup :: Key -> CharMap a -> Maybe a
 lookup k (CharMap m) = M.lookup (C.ord k) m
 
 findWithDefault :: a -> Key -> CharMap a -> a
diff --git a/regex-tdfa.cabal b/regex-tdfa.cabal
--- a/regex-tdfa.cabal
+++ b/regex-tdfa.cabal
@@ -1,5 +1,5 @@
 Name:                   regex-tdfa
-Version:                0.94
+Version:                0.95.1
 -- Cabal-Version:       >=1.1.6
 License:                BSD3
 License-File:           LICENSE