diff --git a/Data/UserId.hs b/Data/UserId.hs
--- a/Data/UserId.hs
+++ b/Data/UserId.hs
@@ -6,6 +6,7 @@
 import Data.Aeson          (FromJSON(..), ToJSON(..), Result(..), fromJSON)
 import Data.Data           (Data)
 import Data.SafeCopy       (SafeCopy, base, deriveSafeCopy)
+import Data.Serialize      (Serialize)
 import Data.Typeable       (Typeable)
 import GHC.Generics        (Generic)
 import Text.Boomerang.TH   (makeBoomerangs)
@@ -14,7 +15,7 @@
 
 -- | a 'UserId' uniquely identifies a user.
 newtype UserId = UserId { _unUserId :: Integer }
-    deriving (Eq, Ord, Enum, Read, Show, Data, Typeable, Generic)
+    deriving (Eq, Ord, Enum, Read, Show, Data, Typeable, Generic, Serialize)
 deriveSafeCopy 1 'base ''UserId
 -- makeLenses ''UserId
 unUserId f (UserId x) = fmap UserId (f x)
diff --git a/userid.cabal b/userid.cabal
--- a/userid.cabal
+++ b/userid.cabal
@@ -1,5 +1,5 @@
 name:                userid
-version:             0.1.2.8
+version:             0.1.3
 synopsis:            The UserId type and useful instances for web development
 description:         Includes instances for SafeCopy, Lens, Boomerang, PathInfo and more
 homepage:            http://www.github.com/Happstack/userid
@@ -21,6 +21,7 @@
   build-depends:       base          >= 4.6  && < 4.10,
                        aeson         >= 0.9  && < 1.2,
                        boomerang     >= 1.4  && < 1.5,
+                       cereal        == 0.5.*,
                        safecopy      >= 0.8  && < 0.10,
                        web-routes    >= 0.27 && < 0.28,
                        web-routes-th >= 0.22 && < 0.23