diff --git a/Data/MessagePack.hs b/Data/MessagePack.hs
--- a/Data/MessagePack.hs
+++ b/Data/MessagePack.hs
@@ -100,7 +100,7 @@
             | size < 0x10000 = putWord8 map16 >> putWord16be (fromIntegral size)
             | otherwise      = putWord8 map32 >> putWord32be (fromIntegral size)
 
-    put (ObjectExt t bytes) = header2 >> putWord8 (fromIntegral t) >> putByteString bytes
+    put (ObjectExt t bytes) = header >> putWord8 (fromIntegral t) >> putByteString bytes
       where
         size = BS.length bytes
         header
diff --git a/messagepack.cabal b/messagepack.cabal
--- a/messagepack.cabal
+++ b/messagepack.cabal
@@ -1,5 +1,5 @@
 name               : messagepack
-version            : 0.5.2
+version            : 0.5.3
 synopsis           : Serialize instance for Message Pack Object
 description        : Serialize instance for Message Pack Object
 homepage           : https://github.com/rodrigosetti/messagepack