diff --git a/moffy-samples-events.cabal b/moffy-samples-events.cabal
--- a/moffy-samples-events.cabal
+++ b/moffy-samples-events.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           moffy-samples-events
-version:        0.2.2.1
+version:        0.2.2.2
 synopsis:       Events for sample codes of moffy
 description:    Please see the README on GitHub at <https://github.com/YoshikuniJujo/moffy-samples-events#readme>
 category:       Control
@@ -61,6 +61,7 @@
     , base >=4.7 && <5
     , bytestring
     , containers
+    , deepseq
     , http-conduit
     , moffy
     , monads-tf
@@ -90,6 +91,7 @@
     , base >=4.7 && <5
     , bytestring
     , containers
+    , deepseq
     , http-conduit
     , moffy
     , moffy-samples-events
diff --git a/src/Control/Moffy/Samples/Followbox/Event.hs b/src/Control/Moffy/Samples/Followbox/Event.hs
--- a/src/Control/Moffy/Samples/Followbox/Event.hs
+++ b/src/Control/Moffy/Samples/Followbox/Event.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE DataKinds, TypeOperators #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE DeriveGeneric #-}
 {-# OPTIONS_GHC -Wall -fno-warn-tabs -fno-warn-orphans #-}
 
 module Control.Moffy.Samples.Followbox.Event (
@@ -28,6 +29,9 @@
 	RaiseError(..), pattern OccRaiseError, Error(..), ErrorResult(..),
 	raiseError, checkTerminate ) where
 
+import GHC.Generics (Generic)
+import Control.DeepSeq
+
 import Control.Moffy (Sig, React, Request(..), await)
 import Control.Moffy.Event.ThreadId (GetThreadId)
 import Control.Moffy.Event.Lock (LockEv)
@@ -151,7 +155,9 @@
 data Error
 	= NoRateLimitRemaining | NoRateLimitReset
 	| NotJson | EmptyJson | NoLoginName | NoAvatarAddress | NoAvatar
-	| NoHtmlUrl | Trace | CatchError deriving (Show, Eq, Ord)
+	| NoHtmlUrl | Trace | CatchError deriving (Show, Eq, Ord, Generic)
+
+instance NFData Error
 
 data ErrorResult = Continue | Terminate deriving Show
 
diff --git a/src/Control/Moffy/Samples/Viewable/Image.hs b/src/Control/Moffy/Samples/Viewable/Image.hs
--- a/src/Control/Moffy/Samples/Viewable/Image.hs
+++ b/src/Control/Moffy/Samples/Viewable/Image.hs
@@ -3,10 +3,14 @@
 {-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE DataKinds, TypeOperators #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE DeriveGeneric #-}
 {-# OPTIONS_GHC -Wall -fno-warn-tabs #-}
 
 module Control.Moffy.Samples.Viewable.Image (Image(..), Png(..)) where
 
+import GHC.Generics
+import Control.DeepSeq
+
 import Data.Type.Set
 import qualified Data.ByteString as BS
 
@@ -14,5 +18,7 @@
 
 data Image = Image' Position Png deriving Show
 data Png = Png { pngWidth :: Double, pngHeight :: Double, pngData :: BS.ByteString }
-	deriving Show
+	deriving (Show, Generic)
 numbered [t| Image |]
+
+instance NFData Png