diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Revision history for finitary-derive
 
+## 2.2.0.0 -- 2019-11-27
+
+* Fix definition of ``Packed`` for ``PackInto`` to actually agree with the
+  documentation.
+
 ## 2.1.0.0 -- 2019-11-24
 
 * Fix bug in ``Ord`` instances for the ``Pack*`` types.
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -114,8 +114,12 @@
 
 ## Sounds good! Can I use it?
 
-Certainly - we've tested on GHC 8.4.4, 8.6.5 and 8.8.1, on GNU/Linux only. If
-you would like support for any additional GHC versions, let us know.
+Certainly - we've tested on the following (all x86_64 only):
+
+* __GNU/Linux:__ GHC 8.4.4, 8.6.5, 8.8.1
+* __macOS:__ GHC 8.8.1
+
+If you would like support for any additional GHC versions, let us know.
 Unfortunately, while the library will _build_ on 8.4.4, due to
 ``hedgehog-classes`` being limited to 8.6+, tests cannot be run on this version.
 
diff --git a/finitary-derive.cabal b/finitary-derive.cabal
--- a/finitary-derive.cabal
+++ b/finitary-derive.cabal
@@ -3,7 +3,7 @@
 -- PVP summary:        +-+------- breaking API changes
 --                     | | +----- non-breaking API additions
 --                     | | | +--- code changes with no API change
-version:               2.1.0.0
+version:               2.2.0.0
 synopsis:              Flexible and easy deriving of type classes for finitary
                        types.
 description:           Provides a collection of wrappers, allowing you to easily
diff --git a/src/Data/Finitary/PackInto.hs b/src/Data/Finitary/PackInto.hs
--- a/src/Data/Finitary/PackInto.hs
+++ b/src/Data/Finitary/PackInto.hs
@@ -107,9 +107,9 @@
 -- mind.
 pattern Packed :: forall (b :: Type) (a :: Type) . 
   (Finitary a, Finitary b, Cardinality a <= Cardinality b) =>
-  PackInto a b -> a
-pattern Packed x <- (packInto -> x)
-  where Packed x = unpackOutOf x
+  a -> PackInto a b
+pattern Packed x <- (unpackOutOf -> x)
+  where Packed x = packInto x
 
 instance (Ord a, Finitary a, Finitary b, Cardinality a <= Cardinality b) => Ord (PackInto a b) where
   {-# INLINE compare #-}