diff --git a/Data/IntMap.hs b/Data/IntMap.hs
--- a/Data/IntMap.hs
+++ b/Data/IntMap.hs
@@ -652,7 +652,7 @@
 
 -- | /O(n+m)/. The union with a combining function.
 --
--- > let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value
+-- > let f key left_value right_value = (show key) ++ ":" ++ left_value ++ "|" ++ right_value
 -- > unionWithKey f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == fromList [(3, "b"), (5, "5:a|A"), (7, "C")]
 
 unionWithKey :: (Key -> a -> a -> a) -> IntMap a -> IntMap a -> IntMap a
diff --git a/Data/Map.hs b/Data/Map.hs
--- a/Data/Map.hs
+++ b/Data/Map.hs
@@ -930,7 +930,7 @@
 -- Union with a combining function. The implementation uses the efficient /hedge-union/ algorithm.
 -- Hedge-union is more efficient on (bigset \``union`\` smallset).
 --
--- > let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value
+-- > let f key left_value right_value = (show key) ++ ":" ++ left_value ++ "|" ++ right_value
 -- > unionWithKey f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == fromList [(3, "b"), (5, "5:a|A"), (7, "C")]
 
 unionWithKey :: Ord k => (k -> a -> a -> a) -> Map k a -> Map k a -> Map k a
diff --git a/containers.cabal b/containers.cabal
--- a/containers.cabal
+++ b/containers.cabal
@@ -1,5 +1,5 @@
 name:       containers
-version:    0.2.0.0
+version:    0.2.0.1
 license:    BSD3
 license-file:    LICENSE
 maintainer:    libraries@haskell.org