diff --git a/List.cabal b/List.cabal
--- a/List.cabal
+++ b/List.cabal
@@ -1,5 +1,5 @@
 Name:                List
-Version:             0.4.4
+Version:             0.5.0
 Category:            Control
 Synopsis:            List monad transformer and class
 Description:
diff --git a/src/Data/List/Class.hs b/src/Data/List/Class.hs
--- a/src/Data/List/Class.hs
+++ b/src/Data/List/Class.hs
@@ -15,9 +15,7 @@
     concat, concatMap,
     tail,
     enumFrom, enumFromTo,
-    catMaybes,
-    -- mapMaybe will be reintroduced in List-0.5.0
-    -- Removed from List-0.4.4 to unbreak hexpat-0.20.2
+    catMaybes, mapMaybe,
     -- Which broke with the release of List-0.4.3 due to unqualified imports.
     -- | Non standard List operations
     foldrL, foldlL, foldl1L, toList, lengthL, lastL,
@@ -354,9 +352,8 @@
         f Nothing = mzero
         f (Just x) = return x
 
--- To be reintroduced in List 0.5.0
--- mapMaybe :: List l => (a -> Maybe b) -> l a -> l b
--- mapMaybe f = catMaybes . liftM f
+mapMaybe :: List l => (a -> Maybe b) -> l a -> l b
+mapMaybe f = catMaybes . liftM f
 
 enumFrom :: (List l, Enum a) => a -> l a
 enumFrom x = cons x (enumFrom (succ x))