diff --git a/Network/HPACK/Context/ReferenceSet.hs b/Network/HPACK/Context/ReferenceSet.hs
--- a/Network/HPACK/Context/ReferenceSet.hs
+++ b/Network/HPACK/Context/ReferenceSet.hs
@@ -19,7 +19,7 @@
 ----------------------------------------------------------------
 
 -- | Type for the reference set.
-data ReferenceSet = ReferenceSet [Index] deriving Show
+newtype ReferenceSet = ReferenceSet [Index] deriving Show
 
 -- | Empty reference set.
 emptyReferenceSet :: ReferenceSet
diff --git a/http2.cabal b/http2.cabal
--- a/http2.cabal
+++ b/http2.cabal
@@ -1,12 +1,15 @@
 Name:                   http2
-Version:                0.0.0
+Version:                0.0.1
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3
 License-File:           LICENSE
 Synopsis:               HTTP/2.0 library including HPACK
 Description:            HTTP/2.0 library including HPACK.
-                        Currently only HPACK 06 is supported.
+                        Currently only (coming) HPACK 06 is supported.
+                        Use Network.HPACK only.
+                        Many modules are exported for debugging
+                        purpose only. Please don't import them.
 Category:               Network
 Cabal-Version:          >= 1.10
 Build-Type:             Simple