diff --git a/msgpack-rpc-conduit.cabal b/msgpack-rpc-conduit.cabal
--- a/msgpack-rpc-conduit.cabal
+++ b/msgpack-rpc-conduit.cabal
@@ -1,5 +1,5 @@
 name:                 msgpack-rpc-conduit
-version:              0.0.6
+version:              0.0.7
 synopsis:             A MessagePack-RPC Implementation
 homepage:             http://msgpack.org/
 license:              BSD3
@@ -54,13 +54,13 @@
     , conduit
     , conduit-extra
     , data-default-class
-    , data-default-instances-base
     , exceptions
     , monad-control
-    , msgpack-binary                    >= 0.0.11
-    , msgpack-types                     >= 0.0.1
+    , monad-validate
+    , msgpack-binary            >= 0.0.11
+    , msgpack-types             >= 0.2 && < 0.3
     , mtl
-    , network                           < 3
+    , network                   < 4
     , text
     , unliftio-core
 
@@ -80,4 +80,4 @@
     , hspec
     , msgpack-rpc-conduit
     , mtl
-    , network                           < 3
+    , network
diff --git a/src/Network/MessagePack/Capabilities.hs b/src/Network/MessagePack/Capabilities.hs
--- a/src/Network/MessagePack/Capabilities.hs
+++ b/src/Network/MessagePack/Capabilities.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE StrictData    #-}
 module Network.MessagePack.Capabilities
     ( ServerCapability (..)
     , ClientCapability (..)
diff --git a/src/Network/MessagePack/Client.hs b/src/Network/MessagePack/Client.hs
--- a/src/Network/MessagePack/Client.hs
+++ b/src/Network/MessagePack/Client.hs
@@ -20,7 +20,6 @@
 import           Control.Monad.Catch                 (catch)
 import qualified Data.ByteString                     as S
 import           Data.Default.Class                  (Default (..))
-import           Data.Default.Instances.Base         ()
 
 import           Network.MessagePack.Capabilities    (ClientCapability (..),
                                                       ServerCapability (..))
diff --git a/src/Network/MessagePack/Client/Internal.hs b/src/Network/MessagePack/Client/Internal.hs
--- a/src/Network/MessagePack/Client/Internal.hs
+++ b/src/Network/MessagePack/Client/Internal.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE MultiParamTypeClasses      #-}
 {-# LANGUAGE OverloadedStrings          #-}
+{-# LANGUAGE StrictData                 #-}
 {-# LANGUAGE TypeFamilies               #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 module Network.MessagePack.Client.Internal where
@@ -11,6 +12,7 @@
 import           Control.Monad.Catch               (MonadCatch, MonadThrow,
                                                     throwM)
 import qualified Control.Monad.State.Strict        as CMS
+import           Control.Monad.Validate            (runValidate)
 import qualified Data.Binary                       as Binary
 import qualified Data.ByteString                   as S
 import           Data.Conduit                      (ConduitT, SealedConduitT,
@@ -18,8 +20,9 @@
                                                     (.|))
 import qualified Data.Conduit.Binary               as CB
 import           Data.Conduit.Serialization.Binary (sinkGet)
-import           Data.MessagePack                  (MessagePack (fromObject),
-                                                    Object)
+import           Data.MessagePack                  (MessagePack, Object,
+                                                    defaultConfig, fromObject,
+                                                    fromObjectWith)
 import           Data.Monoid                       ((<>))
 import           Data.Text                         (Text)
 import qualified Data.Text                         as T
@@ -58,11 +61,11 @@
     => RpcType (ClientT m o) where
   rpcc name args = do
     res <- rpcCall name (reverse args)
-    case fromObject res of
-      R.Success ok  ->
+    case runValidate $ fromObjectWith defaultConfig res of
+      Right ok  ->
         return ok
-      R.Failure msg ->
-        throwM $ ResultTypeError (T.pack msg) res
+      Left err ->
+        throwM $ ResultTypeError (T.pack $ show err) res
 
 
 rpcCall :: (MonadThrow m, CMS.MonadIO m) => Text -> [Object] -> ClientT m Object
@@ -81,8 +84,8 @@
     }
 
   case unpackResponse res of
-    Nothing -> throwM $ ProtocolError "invalid response data"
-    Just (rtype, rmsgid, rerror, rresult) -> do
+    Left err -> throwM $ ProtocolError $ "invalid response data: " <> T.pack (show err)
+    Right (rtype, rmsgid, rerror, rresult) -> do
       when (rtype /= 1) $
         throwM $ ProtocolError $
           "invalid response type (expect 1, but got " <> T.pack (show rtype) <> "): " <> T.pack (show res)
diff --git a/src/Network/MessagePack/Interface.hs b/src/Network/MessagePack/Interface.hs
--- a/src/Network/MessagePack/Interface.hs
+++ b/src/Network/MessagePack/Interface.hs
@@ -6,6 +6,7 @@
 {-# LANGUAGE Safe                  #-}
 {-# LANGUAGE ScopedTypeVariables   #-}
 {-# LANGUAGE StandaloneDeriving    #-}
+{-# LANGUAGE StrictData            #-}
 {-# LANGUAGE TypeFamilies          #-}
 module Network.MessagePack.Interface
     ( Interface (..)
@@ -36,8 +37,8 @@
 
 
 data Interface f = Interface
-  { name :: !Text
-  , docs :: !(Doc f)
+  { name :: Text
+  , docs :: Doc f
   }
 
 
diff --git a/src/Network/MessagePack/Rpc.hs b/src/Network/MessagePack/Rpc.hs
--- a/src/Network/MessagePack/Rpc.hs
+++ b/src/Network/MessagePack/Rpc.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE FlexibleContexts      #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE Safe                  #-}
+{-# LANGUAGE StrictData            #-}
 {-# LANGUAGE TypeFamilies          #-}
 module Network.MessagePack.Rpc
   ( I.Doc (..)
diff --git a/src/Network/MessagePack/Server/Basic.hs b/src/Network/MessagePack/Server/Basic.hs
--- a/src/Network/MessagePack/Server/Basic.hs
+++ b/src/Network/MessagePack/Server/Basic.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE MultiParamTypeClasses      #-}
 {-# LANGUAGE OverloadedStrings          #-}
 {-# LANGUAGE ScopedTypeVariables        #-}
+{-# LANGUAGE StrictData                 #-}
 {-# LANGUAGE Trustworthy                #-}
 {-# LANGUAGE TypeFamilies               #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
@@ -61,6 +62,7 @@
 import           Control.Monad.Trans               (MonadIO, MonadTrans, lift,
                                                     liftIO)
 import           Control.Monad.Trans.Control       (MonadBaseControl)
+import           Control.Monad.Validate            (runValidate)
 import qualified Data.Binary                       as Binary
 import qualified Data.ByteString                   as S
 import           Data.Conduit                      (ConduitT, SealedConduitT,
@@ -74,7 +76,8 @@
 import           Data.Conduit.Serialization.Binary (ParseError, sinkGet)
 import qualified Data.List                         as List
 import           Data.MessagePack                  (MessagePack, Object,
-                                                    fromObject, toObject)
+                                                    defaultConfig, fromObject,
+                                                    fromObjectWith, toObject)
 import           Data.Monoid                       ((<>))
 import qualified Data.Text                         as T
 import           Data.Traversable                  (sequenceA)
@@ -88,7 +91,7 @@
 
 
 newtype ServerT m a = ServerT { runServerT :: m a }
-  deriving (Functor, Applicative, Monad, MonadIO)
+  deriving (Functor, Applicative, Monad, MonadIO, MonadFail)
 
 
 instance MonadTrans ServerT where
@@ -101,13 +104,13 @@
 
 instance (MonadThrow m, MessagePack o, MethodType m r) => MethodType m (o -> r) where
   toBody n f (x : xs) =
-    case fromObject x of
-      Nothing -> throwM $ ServerError "argument type error"
-      Just r  -> toBody n (f r) xs
+    case runValidate . fromObjectWith defaultConfig $ x of
+      Left err -> throwM $ ServerError $ "argument type error: " <> T.pack (show err)
+      Right ok -> toBody n (f ok) xs
   toBody _ _ [] = error "messagepack-rpc methodtype instance toBody failed"
 
 instance (Functor m, MonadThrow m, MessagePack o) => MethodType m (ServerT m o) where
-  toBody _ m [] = toObject <$> runServerT m
+  toBody _ m [] = toObject defaultConfig <$> runServerT m
   toBody n _ ls =
     throwM $ ServerError $
       "invalid arguments for method '" <> n <> "': " <> T.pack (show ls)
@@ -138,11 +141,11 @@
     rsrc $$++ do
       obj <- sinkGet Binary.get
       case unpackRequest obj of
-        Nothing ->
-          throwM $ ServerError "invalid request"
-        Just req@(_, msgid, _, _) ->
+        Left err ->
+          throwM . ServerError . T.pack . show $ err
+        Right req@(_, msgid, _, _) ->
           lift $ getResponse methods req `catch` \(ServerError err) ->
-            return (1, msgid, toObject err, toObject ())
+            return (1, msgid, toObject defaultConfig err, toObject defaultConfig ())
 
   _ <- runConduit $ CB.sourceLbs (packResponse res) .| sink
   processRequests methods rsrc' sink
@@ -156,11 +159,11 @@
 getResponse methods (0, msgid, mth, args) =
   process <$> callMethod methods mth args
   where
-    process (R.Failure err) = (1, msgid, toObject err, toObject ())
-    process (R.Success ok ) = (1, msgid, toObject (), ok)
+    process (R.Failure err) = (1, msgid, toObject defaultConfig err, toObject defaultConfig ())
+    process (R.Success ok ) = (1, msgid, toObject defaultConfig (), ok)
 
 getResponse _ (rtype, msgid, _, _) =
-  pure (1, msgid, toObject ["request type is not 0, got " <> T.pack (show rtype)], toObject ())
+  pure (1, msgid, toObject defaultConfig ["request type is not 0, got " <> T.pack (show rtype)], toObject defaultConfig ())
 
 
 callMethod
diff --git a/src/Network/MessagePack/Types/Client.hs b/src/Network/MessagePack/Types/Client.hs
--- a/src/Network/MessagePack/Types/Client.hs
+++ b/src/Network/MessagePack/Types/Client.hs
@@ -1,10 +1,12 @@
+{-# LANGUAGE Safe #-}
 module Network.MessagePack.Types.Client
   ( RpcType (..)
   , call
   ) where
 
-import           Data.MessagePack (MessagePack (toObject), Object)
-import           Data.Text        (Text)
+import           Data.MessagePack.Types (MessagePack, Object, defaultConfig,
+                                         toObject)
+import           Data.Text              (Text)
 
 
 class RpcType r where
@@ -12,7 +14,7 @@
 
 
 instance (MessagePack o, RpcType r) => RpcType (o -> r) where
-  rpcc name args arg = rpcc name (toObject arg : args)
+  rpcc name args arg = rpcc name (toObject defaultConfig arg : args)
   {-# INLINE rpcc #-}
 
 
diff --git a/src/Network/MessagePack/Types/Error.hs b/src/Network/MessagePack/Types/Error.hs
--- a/src/Network/MessagePack/Types/Error.hs
+++ b/src/Network/MessagePack/Types/Error.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE StrictData         #-}
 module Network.MessagePack.Types.Error
   ( RpcError (..)
   , ServerError (..)
@@ -12,9 +13,9 @@
 
 -- | RPC error type
 data RpcError
-  = RemoteError !Object           -- ^ Server error
-  | ResultTypeError !Text !Object -- ^ Result type mismatch
-  | ProtocolError !Text           -- ^ Protocol error
+  = RemoteError Object          -- ^ Server error
+  | ResultTypeError Text Object -- ^ Result type mismatch
+  | ProtocolError Text          -- ^ Protocol error
   deriving (Show, Eq, Ord, Typeable)
 
 instance Exception RpcError
diff --git a/src/Network/MessagePack/Types/Result.hs b/src/Network/MessagePack/Types/Result.hs
--- a/src/Network/MessagePack/Types/Result.hs
+++ b/src/Network/MessagePack/Types/Result.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE DeriveFunctor     #-}
 {-# LANGUAGE DeriveTraversable #-}
 {-# LANGUAGE Safe              #-}
+{-# LANGUAGE StrictData        #-}
 module Network.MessagePack.Types.Result
     ( Result (..)
     ) where
@@ -30,13 +31,12 @@
     _            <|> r = r
 
 instance Monad Result where
-    return = Success
-    fail = Failure
-
     Success x   >>= f = f x
     Failure msg >>= _ = Failure msg
 
+    return = Success
+
 #if (MIN_VERSION_base(4,13,0))
 instance MonadFail Result where
-    fail = Failure
 #endif
+    fail = Failure
diff --git a/src/Network/MessagePack/Types/Server.hs b/src/Network/MessagePack/Types/Server.hs
--- a/src/Network/MessagePack/Types/Server.hs
+++ b/src/Network/MessagePack/Types/Server.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE Safe                  #-}
+{-# LANGUAGE StrictData            #-}
 module Network.MessagePack.Types.Server
   ( MethodVal (..)
   , MethodDocs (..)
@@ -14,21 +15,21 @@
 
 
 data MethodVal = MethodVal
-  { valName :: !Text
-  , valType :: !Text
+  { valName :: Text
+  , valType :: Text
   }
   deriving (Show, Read, Eq)
 
 data MethodDocs = MethodDocs
-  { methodArgs :: ![MethodVal]
-  , methodRetv :: !MethodVal
+  { methodArgs :: [MethodVal]
+  , methodRetv :: MethodVal
   }
   deriving (Show, Read, Eq)
 
 -- ^ MessagePack RPC method
 data Method m = Method
-  { methodName :: !Text
-  , methodDocs :: !MethodDocs
+  { methodName :: Text
+  , methodDocs :: MethodDocs
   , methodBody :: [Object] -> m Object
   }
 
diff --git a/src/Network/MessagePack/Types/Spec.hs b/src/Network/MessagePack/Types/Spec.hs
--- a/src/Network/MessagePack/Types/Spec.hs
+++ b/src/Network/MessagePack/Types/Spec.hs
@@ -7,9 +7,11 @@
   , unpackResponse
   ) where
 
-import qualified Data.ByteString.Lazy as L
-import qualified Data.List            as List
-import           Data.MessagePack     (MessagePack, Object, fromObject, pack)
+import           Control.Monad.Validate (runValidate)
+import qualified Data.ByteString.Lazy   as L
+import qualified Data.List              as List
+import           Data.MessagePack       (DecodeError, MessagePack, Object,
+                                         defaultConfig, fromObjectWith, pack)
 
 type Request ix = (Int, Int, ix, [Object])
 type Response   = (Int, Int, Object, Object)
@@ -25,8 +27,8 @@
 packResponse :: Response -> L.ByteString
 packResponse = pack
 
-unpackResponse :: Object -> Maybe Response
-unpackResponse = fromObject
+unpackResponse :: Object -> Either DecodeError Response
+unpackResponse = runValidate . fromObjectWith defaultConfig
 
-unpackRequest :: MessagePack ix => Object -> Maybe (Request ix)
-unpackRequest = fromObject
+unpackRequest :: MessagePack ix => Object -> Either DecodeError (Request ix)
+unpackRequest = runValidate . fromObjectWith defaultConfig