diff --git a/examples/pokedex/src/Page/Greet.elm b/examples/pokedex/src/Page/Greet.elm
index d4f60967..547d3222 100644
--- a/examples/pokedex/src/Page/Greet.elm
+++ b/examples/pokedex/src/Page/Greet.elm
@@ -63,15 +63,15 @@ data routeParams =
                             username : String
                             username =
                                 okSession
-                                    |> Dict.get "name"
+                                    |> Session.get "name"
                                     |> Maybe.withDefault "NONAME"
 
                             flashMessage : Maybe String
                             flashMessage =
                                 okSession
-                                    |> Dict.get "message"
+                                    |> Session.get "message"
                         in
-                        ( Session.noUpdates
+                        ( okSession
                         , { username = username
                           , requestTime = requestTime
                           , flashMessage = flashMessage
@@ -84,7 +84,7 @@ data routeParams =
                             |> DataSource.succeed
 
                     _ ->
-                        ( Session.noUpdates, Server.Response.temporaryRedirect "/login" )
+                        ( Session.empty, Server.Response.temporaryRedirect "/login" )
                             |> DataSource.succeed
             )
         ]
diff --git a/examples/pokedex/src/Page/Login.elm b/examples/pokedex/src/Page/Login.elm
index d1cd2fbd..f0b32ad0 100644
--- a/examples/pokedex/src/Page/Login.elm
+++ b/examples/pokedex/src/Page/Login.elm
@@ -51,8 +51,11 @@ data routeParams =
         [ MySession.withSession
             (Request.expectFormPost (\{ field } -> field "name"))
             (\name session ->
-                ( Session.oneUpdate "name" name
-                    |> Session.withFlash "message" ("Welcome " ++ name ++ "!")
+                ( session
+                    |> Result.withDefault Nothing
+                    |> Maybe.withDefault Session.empty
+                    |> Session.insert "name" name
+                    |> Session.withFlash2 "message" ("Welcome " ++ name ++ "!")
                 , "/greet"
                     |> Server.Response.temporaryRedirect
                 )
@@ -63,20 +66,16 @@ data routeParams =
             (\() session ->
                 case session of
                     Ok (Just okSession) ->
-                        ( Session.oneUpdate "name"
-                            (okSession
-                                |> Dict.get "name"
-                                |> Maybe.withDefault "error"
-                            )
+                        ( okSession
                         , okSession
-                            |> Dict.get "name"
+                            |> Session.get "name"
                             |> Data
                             |> Server.Response.render
                         )
                             |> DataSource.succeed
 
                     _ ->
-                        ( Session.noUpdates
+                        ( Session.empty
                         , { username = Nothing }
                             |> Server.Response.render
                         )
diff --git a/src/Session.elm b/src/Session.elm
index 084b0ad6..1e8f2de3 100644
--- a/src/Session.elm
+++ b/src/Session.elm
@@ -136,10 +136,22 @@ succeed constructor =
         |> OptimizedDecoder.succeed
 
 
-setValues : SessionUpdate -> Dict String String -> Json.Encode.Value
-setValues (SessionUpdate dict) original =
-    Dict.union dict original
+setValues : Session -> Json.Encode.Value
+setValues (Session session) =
+    session
         |> Dict.toList
+        |> List.filterMap
+            (\( key, value ) ->
+                case value of
+                    Persistent string ->
+                        Just ( key, string )
+
+                    NewFlash string ->
+                        Just ( flashPrefix ++ key, string )
+
+                    ExpiringFlash _ ->
+                        Nothing
+            )
         |> List.map (Tuple.mapSecond Json.Encode.string)
         |> Json.Encode.object
 
@@ -164,27 +176,34 @@ withSession :
     , sameSite : String
     }
     -> Request request
-    -> (request -> Result String (Maybe (Dict String String)) -> DataSource ( SessionUpdate, Response data ))
+    -> (request -> Result String (Maybe Session) -> DataSource ( Session, Response data ))
     -> Request (DataSource (Response data))
 withSession config userRequest toRequest =
     Request.map2
         (\maybeSessionCookie userRequestData ->
             let
-                decrypted : DataSource (Result String (Maybe (Dict String String)))
+                decrypted : DataSource (Result String (Maybe Session))
                 decrypted =
                     case maybeSessionCookie of
                         Just sessionCookie ->
                             sessionCookie
                                 |> decrypt config.secrets (OptimizedDecoder.dict OptimizedDecoder.string)
                                 |> DataSource.map
-                                    (Dict.Extra.mapKeys
-                                        (\key ->
-                                            if key |> String.startsWith flashPrefix then
-                                                key |> String.dropLeft (flashPrefix |> String.length)
+                                    (\dict ->
+                                        dict
+                                            |> Dict.toList
+                                            |> List.map
+                                                (\( key, value ) ->
+                                                    if key |> String.startsWith flashPrefix then
+                                                        ( key |> String.dropLeft (flashPrefix |> String.length)
+                                                        , ExpiringFlash value
+                                                        )
 
-                                            else
-                                                key
-                                        )
+                                                    else
+                                                        ( key, Persistent value )
+                                                )
+                                            |> Dict.fromList
+                                            |> Session
                                     )
                                 |> DataSource.map (Just >> Ok)
 
@@ -215,7 +234,7 @@ withSession config userRequest toRequest =
                                                 let
                                                     encodedCookie : Json.Encode.Value
                                                     encodedCookie =
-                                                        setValues sessionUpdate (cookieDict |> clearFlashCookies)
+                                                        setValues sessionUpdate
                                                 in
                                                 DataSource.map2
                                                     (\encoded originalCookieValues ->