diff --git a/src/Data/Word/ToolsYj.hs b/src/Data/Word/ToolsYj.hs
--- a/src/Data/Word/ToolsYj.hs
+++ b/src/Data/Word/ToolsYj.hs
@@ -12,6 +12,12 @@
 
 newtype Word4 = Word4_ { unWord4 :: Word8 }
 
+instance Show Word4 where
+	showsPrec p x = showsPrec p (fromIntegral x :: Int)
+
+instance Read Word4 where
+	readsPrec p s = [(fromIntegral (x :: Int), r) | (x, r) <- readsPrec p s]
+
 instance Bits Word4 where
 	Word4_ w1 .&. Word4_ w2 = Word4_ $ w1 .&. w2
 	Word4_ w1 .|. Word4_ w2 = Word4_ $ w1 .|. w2
diff --git a/tools-yj.cabal b/tools-yj.cabal
--- a/tools-yj.cabal
+++ b/tools-yj.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           tools-yj
-version:        0.1.0.43
+version:        0.1.0.44
 synopsis:       Tribial tools
 description:    Please see the README on GitHub at <https://github.com/YoshikuniJujo/tools-yj#readme>
 category:       Tools