diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -3,3 +3,8 @@
 	* Initial version: Serialize instances tested for consistency.
 	* Missing: Extension types
 
+2014-07-25 Rodrigo Setti <rodrigosetti@gmail.com>
+
+	* Fix a fatal bug: Data.MessagePack.Spec was not exposed, thus failing the
+	package installation.
+
diff --git a/Data/MessagePack/Spec.hs b/Data/MessagePack/Spec.hs
new file mode 100644
--- /dev/null
+++ b/Data/MessagePack/Spec.hs
@@ -0,0 +1,102 @@
+{-|
+Module      : Data.MessagePack.Spec
+Description : Message Pack specification values
+Copyright   : (c) Rodrigo Setti, 2014
+License     : MIT
+Maintainer  : rodrigosetti@gmail.com
+Stability   : experimental
+Portability : portable
+
+Define, in a single place, all the message-pack specification binary type
+markers.
+-}
+module Data.MessagePack.Spec where
+
+import Data.Word
+
+posFixintMask = 0x80    -- 10000000
+negFixintMask = 0xe0    -- 11100000
+fixmapMask    = 0xf0    -- 11110000
+fixarrayMask  = 0xf0    -- 11110000
+fixstrMask    = 0xe0    -- 11100000
+
+posFixint = 0x00        -- 0xxxxxxx
+negFixint = 0xe0        -- 111xxxxx
+fixmap    = 0x80        -- 1000xxxx
+fixarray  = 0x90        -- 1001xxxx
+fixstr    = 0xa0        -- 101xxxxx
+nil       = 0xc0        -- 11000000
+false     = 0xc2        -- 11000010
+true      = 0xc3        -- 11000011
+bin8      = 0xc4        -- 11000100
+bin16     = 0xc5        -- 11000101
+bin32     = 0xc6        -- 11000110
+ext8      = 0xc7        -- 11000111
+ext16     = 0xc8        -- 11001000
+ext32     = 0xc9        -- 11001001
+float32   = 0xca        -- 11001010
+float64   = 0xcb        -- 11001011
+uint8     = 0xcc        -- 11001100
+uint16    = 0xcd        -- 11001101
+uint32    = 0xce        -- 11001110
+uint64    = 0xcf        -- 11001111
+int8      = 0xd0        -- 11010000
+int16     = 0xd1        -- 11010001
+int32     = 0xd2        -- 11010010
+int64     = 0xd3        -- 11010011
+fixext1   = 0xd4        -- 11010100
+fixext2   = 0xd5        -- 11010101
+fixext4   = 0xd6        -- 11010110
+fixext8   = 0xd7        -- 11010111
+fixext16  = 0xd8        -- 11011000
+str8      = 0xd9        -- 11011001
+str16     = 0xda        -- 11011010
+str32     = 0xdb        -- 11011011
+array16   = 0xdc        -- 11011100
+array32   = 0xdd        -- 11011101
+map16     = 0xde        -- 11011110
+map32     = 0xdf        -- 11011111
+
+posFixintMask :: Word8
+negFixintMask :: Word8
+fixmapMask    :: Word8
+fixarrayMask  :: Word8
+fixstrMask    :: Word8
+
+posFixint :: Word8
+negFixint :: Word8
+fixmap    :: Word8
+fixarray  :: Word8
+fixstr    :: Word8
+nil       :: Word8
+false     :: Word8
+true      :: Word8
+bin8      :: Word8
+bin16     :: Word8
+bin32     :: Word8
+ext8      :: Word8
+ext16     :: Word8
+ext32     :: Word8
+float32   :: Word8
+float64   :: Word8
+uint8     :: Word8
+uint16    :: Word8
+uint32    :: Word8
+uint64    :: Word8
+int8      :: Word8
+int16     :: Word8
+int32     :: Word8
+int64     :: Word8
+fixext1   :: Word8
+fixext2   :: Word8
+fixext4   :: Word8
+fixext8   :: Word8
+fixext16  :: Word8
+str8      :: Word8
+str16     :: Word8
+str32     :: Word8
+array16   :: Word8
+array32   :: Word8
+map16     :: Word8
+map32     :: Word8
+
diff --git a/messagepack.cabal b/messagepack.cabal
--- a/messagepack.cabal
+++ b/messagepack.cabal
@@ -1,5 +1,5 @@
 name               : messagepack
-version            : 0.1.1
+version            : 0.2.0
 synopsis           : Serialize instance for Message Pack Object
 description        : Serialize instance for Message Pack Object
 homepage           : https://github.com/rodrigosetti/messagepack
@@ -23,6 +23,7 @@
 
 library
   exposed-modules  : Data.MessagePack
+                   , Data.MessagePack.Spec
   default-language : Haskell2010
   build-depends    : base       == 4.*
                    , attoparsec == 0.12.*