diff --git a/Data/Attoparsec/Binary.hs b/Data/Attoparsec/Binary.hs
--- a/Data/Attoparsec/Binary.hs
+++ b/Data/Attoparsec/Binary.hs
@@ -23,7 +23,7 @@
 byteSize :: (Bits a) => a -> Int
 byteSize = (`div` 8) . bitSize
 
-pack :: (Bits a) => B.ByteString -> a
+pack :: (Bits a, Num a) => B.ByteString -> a
 pack = B.foldl' (\n h -> (n `shiftL` 8) .|. fromIntegral h) 0
 
 anyWordN :: (Bits a) => (B.ByteString -> a) -> Parser a
diff --git a/attoparsec-binary.cabal b/attoparsec-binary.cabal
--- a/attoparsec-binary.cabal
+++ b/attoparsec-binary.cabal
@@ -1,7 +1,7 @@
 Name: attoparsec-binary
-Version: 0.1.0.1
+Version: 0.2
 Author: Andrew Drake
-Copyright: (c) 2011 Andrew Drake
+Copyright: (c) 2012 Andrew Drake
 Maintainer: adrake@adrake.org
 Synopsis: Binary processing extensions to Attoparsec.
 Stability: unstable