diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,19 @@
 ## Changelog for the `threepenny-gui` package
 
-**0.4.0.1** -- Bugfix release.
+**0.4.1.0** -- Maintenance release.
 
+* Dependency on `text` package now from version 0.11 to 1.1.*.
+* Dependency on `aeson` package replaces the former dependency on the `json` package.
+* Unicode characters are now transmitted correctly to the browser. #75, #62.
+* Change default port number to 8023. #64
+
+**0.4.0.2** -- Bugfix release.
+
 * Fix CSS bug for `grid` function.
+
+**0.4.0.1** -- Maintenance release.
+
+* Adjust package dependencies.
 
 **0.4.0.0** -- Snapshot release.
 
diff --git a/samples/BarTab.hs b/samples/BarTab.hs
--- a/samples/BarTab.hs
+++ b/samples/BarTab.hs
@@ -11,7 +11,7 @@
 
 -- | Main entry point.
 main :: IO ()
-main = startGUI defaultConfig { tpPort = 10000 } setup
+main = startGUI defaultConfig setup
 
 setup :: Window -> UI ()
 setup w = do
diff --git a/samples/Buttons.hs b/samples/Buttons.hs
--- a/samples/Buttons.hs
+++ b/samples/Buttons.hs
@@ -13,10 +13,7 @@
 main :: IO ()
 main = do
     static <- getStaticDir
-    startGUI defaultConfig
-        { tpPort       = 10000
-        , tpStatic     = Just static
-        } setup
+    startGUI defaultConfig { tpStatic = Just static } setup
 
 setup :: Window -> UI ()
 setup w = void $ do
diff --git a/samples/CRUD.hs b/samples/CRUD.hs
--- a/samples/CRUD.hs
+++ b/samples/CRUD.hs
@@ -24,7 +24,7 @@
     Main
 ------------------------------------------------------------------------------}
 main :: IO ()
-main = startGUI defaultConfig { tpPort = 10000 } setup
+main = startGUI defaultConfig setup
 
 setup :: Window -> UI ()
 setup window = void $ mdo
diff --git a/samples/Chat.hs b/samples/Chat.hs
--- a/samples/Chat.hs
+++ b/samples/Chat.hs
@@ -22,8 +22,7 @@
     static   <- getStaticDir
     messages <- Chan.newChan
     startGUI defaultConfig
-        { tpPort       = 10000
-        , tpCustomHTML = Just "chat.html"
+        { tpCustomHTML = Just "chat.html"
         , tpStatic     = Just static
         } $ setup messages
 
diff --git a/samples/CurrencyConverter.hs b/samples/CurrencyConverter.hs
--- a/samples/CurrencyConverter.hs
+++ b/samples/CurrencyConverter.hs
@@ -10,7 +10,7 @@
     Main
 ------------------------------------------------------------------------------}
 main :: IO ()
-main = startGUI defaultConfig { tpPort = 10000 } setup
+main = startGUI defaultConfig setup
 
 setup :: Window -> UI ()
 setup window = void $ do
diff --git a/samples/DragNDropExample.hs b/samples/DragNDropExample.hs
--- a/samples/DragNDropExample.hs
+++ b/samples/DragNDropExample.hs
@@ -14,10 +14,7 @@
 main :: IO ()
 main = do
     static <- getStaticDir
-    startGUI defaultConfig
-        { tpPort       = 10000
-        , tpStatic     = Just static
-        } setup
+    startGUI defaultConfig { tpStatic = Just static } setup
 
 setup :: Window -> UI ()
 setup w = void $ do
diff --git a/samples/DrumMachine.hs b/samples/DrumMachine.hs
--- a/samples/DrumMachine.hs
+++ b/samples/DrumMachine.hs
@@ -30,7 +30,7 @@
     Main
 ------------------------------------------------------------------------------}
 main :: IO ()
-main = startGUI defaultConfig { tpPort = 10000 } setup
+main = startGUI defaultConfig setup
 
 setup :: Window -> UI ()
 setup w = void $ do
diff --git a/samples/MissingDollars.hs b/samples/MissingDollars.hs
--- a/samples/MissingDollars.hs
+++ b/samples/MissingDollars.hs
@@ -12,10 +12,7 @@
 main :: IO ()
 main = do
     static <- getStaticDir
-    startGUI defaultConfig
-        { tpPort       = 10000
-        , tpStatic     = Just static
-        } setup
+    startGUI defaultConfig { tpStatic = Just static } setup
 
 
 setup :: Window -> UI ()
diff --git a/samples/UseWords.hs b/samples/UseWords.hs
--- a/samples/UseWords.hs
+++ b/samples/UseWords.hs
@@ -17,10 +17,7 @@
 main :: IO ()
 main = do
     static <- getStaticDir
-    startGUI defaultConfig
-        { tpPort       = 10000
-        , tpStatic     = Just static
-        } setup
+    startGUI defaultConfig { tpStatic = Just static } setup
 
 
 setup :: Window -> UI ()
diff --git a/src/Graphics/UI/Threepenny/Attributes.hs b/src/Graphics/UI/Threepenny/Attributes.hs
--- a/src/Graphics/UI/Threepenny/Attributes.hs
+++ b/src/Graphics/UI/Threepenny/Attributes.hs
@@ -18,7 +18,7 @@
     target, text_, type_, usemap, valign, version, vlink, vspace, width,
     ) where
 
-import Text.JSON
+import qualified Data.Aeson       as JSON
 import Graphics.UI.Threepenny.Core
 
 {-----------------------------------------------------------------------------
@@ -26,20 +26,21 @@
 ------------------------------------------------------------------------------}
 -- | The @checked@ status of an input element of type checkbox.
 checked :: Attr Element Bool
-checked = fromProp "checked" (== JSBool True) JSBool
+checked = fromProp "checked" (== JSON.Bool True) JSON.Bool
 
 -- | The @enabled@ status of an input element
 enabled :: Attr Element Bool
-enabled = fromProp "disabled" (== JSBool False) (JSBool . not)
+enabled = fromProp "disabled" (== JSON.Bool False) (JSON.Bool . not)
 
 -- | Index of the currently selected option of a @<select>@ element.
 --
 -- The index starts at @0@.
 -- If no option is selected, then the selection is 'Nothing'.
 selection :: Attr Element (Maybe Int)
-selection = fromProp "selectedIndex" from (showJSON . maybe (-1) id)
+selection = fromProp "selectedIndex" from (JSON.toJSON . maybe (-1) id)
     where
-    from s = let Ok x = readJSON s in if x == -1 then Nothing else Just x
+    from s = let JSON.Success x = JSON.fromJSON s in 
+        if x == -1 then Nothing else Just x
 
 
 {-----------------------------------------------------------------------------
diff --git a/src/Graphics/UI/Threepenny/Core.hs b/src/Graphics/UI/Threepenny/Core.hs
--- a/src/Graphics/UI/Threepenny/Core.hs
+++ b/src/Graphics/UI/Threepenny/Core.hs
@@ -71,7 +71,7 @@
 import qualified Control.Monad.Trans.RWS.Lazy as Monad
 
 import Network.URI
-import Text.JSON
+import qualified Data.Aeson as JSON
 
 import           Reactive.Threepenny hiding (onChange)
 import qualified Reactive.Threepenny as Reactive
@@ -355,7 +355,7 @@
 audioStop el = runFunction $ ffi "prim_audio_stop(%1)" el
 
 -- Turn a jQuery property @.prop()@ into an attribute.
-fromProp :: String -> (JSValue -> a) -> (a -> JSValue) -> Attr Element a
+fromProp :: String -> (JSON.Value -> a) -> (a -> JSON.Value) -> Attr Element a
 fromProp name from to = mkReadWriteAttr get set
     where
     set v el = runFunction $ ffi "$(%1).prop(%2,%3)" el name (to v)
diff --git a/src/Graphics/UI/Threepenny/Internal/Driver.hs b/src/Graphics/UI/Threepenny/Internal/Driver.hs
--- a/src/Graphics/UI/Threepenny/Internal/Driver.hs
+++ b/src/Graphics/UI/Threepenny/Internal/Driver.hs
@@ -72,7 +72,7 @@
 import           Data.Maybe
 import           Data.Text                     (Text,pack,unpack)
 import qualified Data.Text                     as Text
-import           Data.Text.Encoding
+import           Data.Text.Encoding            as Text
 import           Data.Time
 import           Network.URI
 import qualified Network.WebSockets            as WS
@@ -83,10 +83,14 @@
 import           Snap.Core
 import qualified Snap.Http.Server              as Snap
 import           Snap.Util.FileServe
+import           System.Environment            (getEnvironment)
 import           System.FilePath
-import qualified Text.JSON as JSON
-import           Text.JSON.Generic
 
+import qualified Data.Aeson                    as JSON
+import           Data.Aeson                    (Result(..))
+import           Data.Aeson.Generic
+import qualified Data.ByteString.Lazy.Char8    as LBS
+import           Data.Data
 
 import           Graphics.UI.Threepenny.Internal.Types     as Threepenny
 import           Graphics.UI.Threepenny.Internal.Resources
@@ -109,10 +113,13 @@
 --   worker action.
 serve :: Config -> (Session -> IO ()) -> IO ()
 serve Config{..} worker = do
+    env    <- getEnvironment
+    let portEnv = Safe.readMay =<< Prelude.lookup "PORT" env
+    
     server <- newServerState
     _      <- forkIO $ custodian 30 (sSessions server)
-    let config = Snap.setPort tpPort
-               $ Snap.setErrorLog (Snap.ConfigIoLog tpLog)
+    let config = Snap.setPort      (maybe defaultPort id (tpPort `mplus` portEnv))
+               $ Snap.setErrorLog  (Snap.ConfigIoLog tpLog)
                $ Snap.setAccessLog (Snap.ConfigIoLog tpLog)
                $ Snap.defaultConfig
     Snap.httpServe config . route $
@@ -239,14 +246,11 @@
 -- | Handle signals sent from the client.
 signal :: Session -> Snap ()
 signal Session{..} = do
-    input <- getInput "signal"
-    case input of
-      Just signalJson -> do
-        let signal = JSON.decode signalJson
-        case signal of
-          Ok signal -> liftIO $ writeChan sSignals signal
-          Error err -> error err
-      Nothing -> error $ "Unable to parse " ++ show input
+    input <- getParam "signal"
+    let err = error $ "Unable to parse " ++ show input
+    case JSON.decode . LBS.fromStrict =<< input of
+        Just    signal -> liftIO $ writeChan sSignals signal
+        Nothing        -> err
 
 {-----------------------------------------------------------------------------
     Implementation of two-way communication
@@ -273,17 +277,19 @@
     sendData <- forkIO . forever $ do
         x <- readChan sInstructions
         -- see note [Instruction strictness]
-        WS.sendTextData connection . Text.pack . JSON.encode $ x
+        WS.sendTextData connection . JSON.encode $ x
 
     -- read data
     let readData = do
             input <- WS.receiveData connection
             case input of
-                "ping" -> WS.sendTextData connection . Text.pack $ "pong"
+                "ping" -> WS.sendTextData connection . LBS.pack $ "pong"
                 "quit" -> E.throw WS.ConnectionClosed
-                input  -> case JSON.decode . Text.unpack $ input of
-                    Ok signal -> writeChan sSignals signal
-                    Error err -> E.throw $ Atto.ParseError [] err
+                input  -> case JSON.decode input of
+                    Just signal -> writeChan sSignals signal
+                    Nothing     -> E.throw $ Atto.ParseError [] $
+                        "Threepenny.Internal.Core: Couldn't parse 'Signal' "
+                        ++ show input
     
     forever readData `E.finally`
         (do
@@ -370,8 +376,8 @@
     call window (CallJSFunction . toCode $ jsfunction) $ \signal ->
         case signal of
             FunctionResult v -> case marshalResult jsfunction window v of
-                Ok    a -> return $ Just a
-                Error _ -> return Nothing
+                Success a -> return $ Just a
+                Error   _ -> return Nothing
             _ -> return Nothing
 
 
@@ -395,14 +401,14 @@
     Snap utilities
 ------------------------------------------------------------------------------}
 -- Write JSON to output.
-writeJson :: (MonadSnap m, JSON a) => a -> m ()
+writeJson :: (MonadSnap m, JSON.ToJSON a) => a -> m ()
 writeJson json = do
     modifyResponse $ setContentType "application/json"
-    (writeText . pack . (\x -> showJSValue x "") . showJSON) json
+    writeLBS . JSON.encode $ json
 
 -- Get a text input from snap.
 getInput :: (MonadSnap f) => ByteString -> f (Maybe String)
-getInput = fmap (fmap (unpack . decodeUtf8)) . getParam
+getInput = fmap (fmap (unpack . Text.decodeUtf8)) . getParam
 
 -- Read an input from snap.
 readInput :: (MonadSnap f,Read a) => ByteString -> f (Maybe a)
diff --git a/src/Graphics/UI/Threepenny/Internal/FFI.hs b/src/Graphics/UI/Threepenny/Internal/FFI.hs
--- a/src/Graphics/UI/Threepenny/Internal/FFI.hs
+++ b/src/Graphics/UI/Threepenny/Internal/FFI.hs
@@ -9,17 +9,38 @@
     FFI(..), ToJS(..),
     JSFunction,
     
+    showJSON,
+    
     toCode, marshalResult,
     ) where
 
-import           Data.Functor
+import           Data.Aeson            as JSON
+import qualified Data.Aeson.Types      as JSON
+import qualified Data.Aeson.Encode
 import           Data.ByteString       (ByteString)
-import qualified Data.ByteString.Char8 as BS
-import           Text.JSON.Generic
+import           Data.Data
+import           Data.Functor
+import           Data.Maybe
+import           Data.String           (fromString)
+import qualified Data.Text.Lazy
+import qualified Data.Text.Lazy.Builder
 
+import Safe (atMay)
+
 import Graphics.UI.Threepenny.Internal.Types
 
 {-----------------------------------------------------------------------------
+    Easy, if stupid conversion between String and JSON
+
+    TODO: Use more efficient string types like ByteString, Text, etc.
+------------------------------------------------------------------------------}
+showJSON :: ToJSON a => a -> String
+showJSON
+    = Data.Text.Lazy.unpack
+    . Data.Text.Lazy.Builder.toLazyText
+    . Data.Aeson.Encode.fromValue . JSON.toJSON
+
+{-----------------------------------------------------------------------------
     JavaScript Code and Foreign Function Interface
 ------------------------------------------------------------------------------}
 -- | JavaScript code snippet.
@@ -30,10 +51,11 @@
 class ToJS a where
     render :: a -> JSCode
 
-instance ToJS String     where render   = JSCode . show
+instance ToJS String     where render   = render . JSON.String . fromString
 instance ToJS Int        where render   = JSCode . show
 instance ToJS Bool       where render b = JSCode $ if b then "false" else "true"
-instance ToJS JSValue    where render x = JSCode $ showJSValue x ""
+instance ToJS JSON.Value where render   = JSCode . showJSON
+-- TODO: ByteString instance may be wrong. Only needed for ElementId right now.
 instance ToJS ByteString where render   = JSCode . show
 instance ToJS ElementId  where
     render (ElementId x) = apply "elidToElement(%1)" [render x]
@@ -42,8 +64,9 @@
 
 -- | A JavaScript function with a given output type @a@.
 data JSFunction a = JSFunction
-    { code    :: JSCode                          -- code snippet
-    , marshal :: Window -> JSValue -> Result a   -- convert to Haskell value
+    { code    :: JSCode                                  -- ^ code snippet
+    , marshal :: Window -> JSON.Value -> JSON.Parser a
+      -- ^ conversion to Haskell value
     }
 
 -- | Render function to a textual representation using JavaScript syntax.
@@ -52,11 +75,11 @@
 
 -- | Convert function result to a Haskell value.
 marshalResult
-    :: JSFunction a -- ^ Function that has been executed
-    -> Window       -- ^ Browser context
-    -> JSValue      -- ^ JSON representation of the return value 
-    -> Result a     -- ^ 
-marshalResult = marshal
+    :: JSFunction a   -- ^ Function that has been executed
+    -> Window         -- ^ Browser context
+    -> JSON.Value     -- ^ JSON representation of the return value 
+    -> JSON.Result a  -- ^ Function result as parsed Haskell value
+marshalResult fun w = JSON.parse (marshal fun w)
 
 instance Functor JSFunction where
     fmap f = fmapWindow (const f)
@@ -65,7 +88,7 @@
 fmapWindow f (JSFunction c m) = JSFunction c (\w v -> f w <$> m w v)
 
 fromJSCode :: JSCode -> JSFunction ()
-fromJSCode c = JSFunction { code = c, marshal = \_ _ -> Ok () }
+fromJSCode c = JSFunction { code = c, marshal = \_ _ -> return () }
 
 -- | Helper class for making 'ffi' a variable argument function.
 class FFI a where
@@ -74,10 +97,10 @@
 instance (ToJS a, FFI b) => FFI (a -> b) where
     fancy f a = fancy $ f . (render a:)
 
-instance FFI (JSFunction ())         where fancy f = fromJSCode $ f []
-instance FFI (JSFunction String)     where fancy   = mkResult "%1.toString()"
-instance FFI (JSFunction JSValue)    where fancy   = mkResult "%1"
-instance FFI (JSFunction [ElementId]) where fancy  = mkResult "elementsToElids(%1)"
+instance FFI (JSFunction ())          where fancy f = fromJSCode $ f []
+instance FFI (JSFunction String)      where fancy   = mkResult "%1.toString()"
+instance FFI (JSFunction JSON.Value)  where fancy   = mkResult "%1"
+instance FFI (JSFunction [ElementId]) where fancy   = mkResult "elementsToElids(%1)"
 
 -- FIXME: We need access to IO in order to turn a Coupon into an Element.
 {- 
@@ -85,10 +108,10 @@
     fancy   = fmapWindow (\w elid -> Element elid w) . fancy
 -}
 
-mkResult :: JSON a => String -> ([JSCode] -> JSCode) -> JSFunction a
+mkResult :: FromJSON a => String -> ([JSCode] -> JSCode) -> JSFunction a
 mkResult client f = JSFunction
     { code    = apply client [f []]
-    , marshal = \w -> readJSON
+    , marshal = \w -> parseJSON
     }
 
 -- | Simple JavaScript FFI with string substitution.
@@ -121,7 +144,9 @@
 apply :: String -> [JSCode] -> JSCode
 apply code args = JSCode $ go code
     where
-    argument i = unJSCode (args !! i)
+    at xs i = maybe (error err) id $ atMay xs i
+    err     = "Graphics.UI.Threepenny.FFI: Too few arguments in FFI call!"
+    argument i = unJSCode (args `at` i)
     
     go []         = []
     go ('%':c:cs) = argument index ++ go cs
diff --git a/src/Graphics/UI/Threepenny/Internal/Include.hs b/src/Graphics/UI/Threepenny/Internal/Include.hs
--- a/src/Graphics/UI/Threepenny/Internal/Include.hs
+++ b/src/Graphics/UI/Threepenny/Internal/Include.hs
@@ -6,12 +6,15 @@
 import qualified Language.Haskell.TH as TH
 import Language.Haskell.TH.Quote
 
-#ifdef CABAL
+#if defined(CABAL) || defined(FPCOMPLETE)
+root :: FilePath
 root = "src/"
 #else
+root :: FilePath
 root = "../src/" -- running examples from ghci
 #endif
 
+include :: QuasiQuoter
 include = QuasiQuoter
         { quoteExp  = f             -- only used as an expression,
         , quotePat  = undefined     -- hence all other use cases undefined
@@ -21,6 +24,7 @@
     where
     f s = TH.LitE . TH.StringL <$> TH.runIO (readFileUTF8 $ root ++ s)
 
+readFileUTF8 :: FilePath -> IO String
 readFileUTF8 path = do
     h <- openFile path ReadMode
     hSetEncoding h utf8
diff --git a/src/Graphics/UI/Threepenny/Internal/Types.hs b/src/Graphics/UI/Threepenny/Internal/Types.hs
--- a/src/Graphics/UI/Threepenny/Internal/Types.hs
+++ b/src/Graphics/UI/Threepenny/Internal/Types.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -9,6 +10,7 @@
 import Control.Applicative
 import Control.Concurrent
 import Control.DeepSeq
+import Control.Monad
 import qualified Reactive.Threepenny    as E
 import           Data.ByteString.Char8  (ByteString)
 import qualified Data.ByteString.Char8  as BS
@@ -17,7 +19,11 @@
 import Data.Time
 
 import Network.URI
-import Text.JSON.Generic
+import Data.Data
+import           Data.Aeson             as JSON
+import qualified Data.Aeson.Types       as JSON
+import qualified Data.Aeson.Generic
+
 import System.IO (stderr)
 import System.IO.Unsafe
 
@@ -39,11 +45,15 @@
 
 instance NFData ElementId where
     rnf (ElementId x) =
+#if defined(CABAL) || defined(FPCOMPLETE)
 #if MIN_VERSION_bytestring(0, 10, 0)
         rnf x
 #else
         BS.length x `seq` ()
 #endif
+#else
+        rnf x
+#endif
 
 type EventId  = String
 type Handlers = Map EventId (E.Handler EventData)
@@ -51,11 +61,11 @@
 
 
 -- Marshalling ElementId
-instance JSON ElementId where
-  showJSON (ElementId o) = showJSON o
-  readJSON obj = do
-    obj <- readJSON obj
-    ElementId <$> valFromObj "Element" obj
+instance ToJSON ElementId where
+    toJSON (ElementId o)  = toJSON o
+instance FromJSON ElementId where
+    parseJSON (Object v)  = ElementId <$> v .: "Element"
+    parseJSON _           = mzero
 
 
 -- | Perform an action on the element.
@@ -149,18 +159,29 @@
 
 -- | Record for configuring the Threepenny GUI server.
 data Config = Config
-  { tpPort       :: Int                 -- ^ Port number.
-  , tpCustomHTML :: Maybe FilePath      -- ^ Custom HTML file to replace the default one.
-  , tpStatic     :: Maybe FilePath      -- ^ Directory that is served under @/static@.
-  , tpLog        :: ByteString -> IO () -- ^ Print a single log message.
-  }
+    { tpPort       :: Maybe Int           
+        -- ^ Port number.
+        -- @Nothing@ means that the port number is
+        -- read from the environment variable @PORT@.
+        -- Alternatively, port @8023@ is used if this variable is not set.
+    , tpCustomHTML :: Maybe FilePath
+        -- ^ Custom HTML file to replace the default one.
+    , tpStatic     :: Maybe FilePath
+        -- ^ Directory that is served under @/static@.
+    , tpLog        :: ByteString -> IO ()
+        -- ^ Print a single log message.
+    }
 
+defaultPort :: Int
+defaultPort = 8023
+
 -- | Default configuration.
 --
--- Port 10000, no custom HTML, no static directory, logging to stderr.
+-- Port from environment variable or @8023@,
+-- no custom HTML, no static directory, logging to stderr.
 defaultConfig :: Config
 defaultConfig = Config
-    { tpPort       = 10000
+    { tpPort       = Nothing
     , tpCustomHTML = Nothing
     , tpStatic     = Nothing
     , tpLog        = \s -> BS.hPut stderr s >> BS.hPut stderr "\n"
@@ -182,9 +203,8 @@
   | Delete ElementId
   deriving (Typeable,Data,Show)
 
-instance JSON Instruction where
-    readJSON _ = error "JSON.Instruction.readJSON: No method implemented."
-    showJSON x = toJSON x 
+instance ToJSON Instruction where
+    toJSON x = Data.Aeson.Generic.toJSON x 
 
 instance NFData Instruction where
     rnf (Debug    x  ) = rnf x
@@ -202,29 +222,28 @@
   | Event ElementId EventId [Maybe String]
   | Values [String]
   | FunctionCallValues [Maybe String]
-  | FunctionResult JSValue
+  | FunctionResult JSON.Value
   deriving (Typeable,Show)
 
-instance JSON Signal where
-  showJSON _ = error "JSON.Signal.showJSON: No method implemented."
-  readJSON obj = do
-    obj <- readJSON obj
-    let quit     = Quit <$> valFromObj "Quit" obj
+instance FromJSON Signal where
+  parseJSON (Object v) = do
+    let quit  = Quit <$> v .: "Quit"
         event = do
-          e         <- valFromObj "Event" obj
-          elid      <- valFromObj "Element" e
-          eventId   <- valFromObj "EventId" e
-          arguments <- valFromObj "Params"  e
+          e         <- v .: "Event"
+          elid      <- e .: "Element"
+          eventId   <- e .: "EventId"
+          arguments <- e .: "Params"
           args      <- mapM nullable arguments
           return $ Event elid eventId args
-        values = Values <$> valFromObj "Values" obj
+        values = Values <$> v .: "Values"
         fcallvalues = do
-          FunctionCallValues <$> (valFromObj "FunctionCallValues" obj >>= mapM nullable)
-        fresult = FunctionResult <$> valFromObj "FunctionResult" obj
+          FunctionCallValues <$> (v .: "FunctionCallValues" >>= mapM nullable)
+        fresult = FunctionResult <$> v .: "FunctionResult"
     quit <|> event <|> values <|> fcallvalues <|> fresult
+  parseJSON _        = mzero
 
--- | Read a JSValue that may be null.
-nullable :: JSON a => JSValue -> Result (Maybe a)
-nullable JSNull = return Nothing
-nullable v      = Just <$> readJSON v
+-- | Read a JSON Value that may be null.
+nullable :: FromJSON a => JSON.Value -> JSON.Parser (Maybe a)
+nullable Null = return Nothing
+nullable v    = Just <$> parseJSON v
 
diff --git a/src/Graphics/UI/Threepenny/JQuery.hs b/src/Graphics/UI/Threepenny/JQuery.hs
--- a/src/Graphics/UI/Threepenny/JQuery.hs
+++ b/src/Graphics/UI/Threepenny/JQuery.hs
@@ -2,15 +2,18 @@
 module Graphics.UI.Threepenny.JQuery where
 
 import Control.Arrow
+import           Data.Aeson                 as JSON
+import Data.String
 import Data.Char
 import Data.Default
 import Data.Maybe
 import Graphics.UI.Threepenny.Core
+import Graphics.UI.Threepenny.Internal.FFI    (showJSON)
 import qualified Graphics.UI.Threepenny.Internal.Driver as Core
-import qualified Graphics.UI.Threepenny.Internal.Types as Core
-import Text.JSON
+import qualified Graphics.UI.Threepenny.Internal.Types  as Core
 import Reactive.Threepenny
 
+
 data Easing = Swing | Linear
   deriving (Eq,Enum,Show)
 
@@ -23,8 +26,10 @@
     Core.withElement (toElement el) $ \elid window ->
         callDeferredFunction window
             "jquery_animate"
-            [encode elid,encode (makeObj (map (second showJSON) props)),show duration,map toLower (show easing)]
+            [showJSON elid,showJSON propsJSON,show duration,map toLower (show easing)]
             (const complete)
+    where
+    propsJSON = JSON.object [fromString name .= val | (name,val) <- props]
 
 -- | Fade in an element.
 fadeIn :: Element -> Int -> Easing -> IO () -> IO ()
diff --git a/src/Reactive/Threepenny/Monads.hs b/src/Reactive/Threepenny/Monads.hs
--- a/src/Reactive/Threepenny/Monads.hs
+++ b/src/Reactive/Threepenny/Monads.hs
@@ -8,5 +8,5 @@
 ------------------------------------------------------------------------------}
 runEvalP :: Values -> EvalP a -> IO (a, Values)
 runEvalP pulses m = do
-    (a, s, w) <- runRWST m () pulses
+    (a, s, _) <- runRWST m () pulses
     return (a, s)
diff --git a/src/Reactive/Threepenny/Types.hs b/src/Reactive/Threepenny/Types.hs
--- a/src/Reactive/Threepenny/Types.hs
+++ b/src/Reactive/Threepenny/Types.hs
@@ -1,7 +1,7 @@
 module Reactive.Threepenny.Types where
 
 import Control.Monad.Trans.RWS.Lazy
-import Data.Functor.Identity
+import Data.Functor.Identity ()
 
 import           Data.Hashable
 import qualified Data.Vault.Strict   as Vault.Strict
diff --git a/threepenny-gui.cabal b/threepenny-gui.cabal
--- a/threepenny-gui.cabal
+++ b/threepenny-gui.cabal
@@ -1,5 +1,5 @@
 Name:                threepenny-gui
-Version:             0.4.0.2
+Version:             0.4.1.0
 Synopsis:            GUI framework that uses the web browser as a display.
 Description:
     Threepenny-GUI is a GUI framework that uses the web browser as a display.
@@ -92,6 +92,7 @@
       cpp-options:  -DREBUG
       ghc-options:  -O2   
   build-depends:     base                   >= 4     && < 5
+                    ,aeson                  == 0.6.*
                     ,attoparsec-enumerator  == 0.3.*
                     ,bytestring             >= 0.9.2 && < 0.11
                     ,containers             >= 0.4.2 && < 0.6
@@ -99,7 +100,6 @@
                     ,deepseq                == 1.3.*
                     ,filepath               == 1.3.*
                     ,hashable               >= 1.1.0  && < 1.3
-                    ,json                   >= 0.4.4  && < 0.8
                     ,MonadCatchIO-transformers == 0.3.*
                     ,network                >= 2.3.0  && < 2.5
                     ,safe                   == 0.3.*
@@ -107,7 +107,7 @@
                     ,snap-core              == 0.9.*
                     ,stm                    >= 2.3    && < 2.5
                     ,template-haskell       >= 2.7.0  && < 2.9
-                    ,text                   == 0.11.*
+                    ,text                   >= 0.11   && < 1.2
                     ,time                   == 1.4.*
                     ,transformers           == 0.3.*
                     ,unordered-containers   == 0.2.*