diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -3,3 +3,5 @@
 [![CircleCI](https://circleci.com/gh/ejconlon/int-like/tree/master.svg?style=svg)](https://circleci.com/gh/ejconlon/int-like/tree/master)
 
 Newtype wrappers over `IntSet` and `IntMap`
+
+Never mix up `Int` newtypes again! Instead of working directly with an `IntSet`, you can work with `IntLikeSet MyIntNewtype` with more or less the same API. You might have to thread through some `Coercible` constraints, though.
diff --git a/int-like.cabal b/int-like.cabal
--- a/int-like.cabal
+++ b/int-like.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           int-like
-version:        0.1.0
+version:        0.1.1
 synopsis:       Newtype wrappers over IntSet and IntMap
 description:    Please see the README on GitHub at <https://github.com/ejconlon/int-like#readme>
 category:       Data Structures
diff --git a/src/IntLike/Map.hs b/src/IntLike/Map.hs
--- a/src/IntLike/Map.hs
+++ b/src/IntLike/Map.hs
@@ -8,6 +8,7 @@
   , member
   , toList
   , keys
+  , keysSet
   , elems
   , lookup
   , partialLookup
@@ -22,6 +23,7 @@
   , restrictKeys
   , map
   , insertState
+  , mapWithKey
   ) where
 
 import Control.DeepSeq (NFData)
@@ -67,6 +69,10 @@
 keys = coerce . IntMap.keys . unIntLikeMap
 {-# INLINE keys #-}
 
+keysSet :: IntLikeMap x a -> IntLikeSet x
+keysSet = IntLikeSet . IntMap.keysSet . unIntLikeMap
+{-# INLINE keysSet #-}
+
 elems :: IntLikeMap x a -> [a]
 elems = IntMap.elems . unIntLikeMap
 {-# INLINE elems #-}
@@ -122,3 +128,7 @@
 insertState :: Coercible x Int => (Maybe a -> b) -> x -> a -> IntLikeMap x a -> (b, IntLikeMap x a)
 insertState f x a = coerce . IntMap.alterF (\m -> (f m, Just a)) (coerce x) . unIntLikeMap
 {-# INLINE insertState #-}
+
+mapWithKey :: Coercible x Int => (x -> a -> b) -> IntLikeMap x a -> IntLikeMap x b
+mapWithKey f = IntLikeMap . IntMap.mapWithKey (coerce f) . unIntLikeMap
+{-# INLINE mapWithKey #-}