diff --git a/NaCl.cabal b/NaCl.cabal
--- a/NaCl.cabal
+++ b/NaCl.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 02b4db73a797bd9fea66be22ae988908a6417d2d841dcce7d53ecba29b09c985
+-- hash: 1a62f7dc222dc8ad85a2dec5e6789c2ea3adaa30dbbfcb5b89a40e1c62f4126a
 
 name:           NaCl
-version:        0.0.3.0
+version:        0.0.3.1
 synopsis:       Easy-and-safe-to-use high-level Haskell bindings to NaCl
 description:    This library uses <https://libsodium.org Sodium> under the hood,
                 but only exposes the primitives that are part of the “classic” NaCl
diff --git a/lib/Crypto/Box/Internal.hs b/lib/Crypto/Box/Internal.hs
--- a/lib/Crypto/Box/Internal.hs
+++ b/lib/Crypto/Box/Internal.hs
@@ -39,6 +39,7 @@
 -- | Public key that can be used for Box.
 type PublicKey = SizedByteArray Na.CRYPTO_BOX_PUBLICKEYBYTES ByteString
 
+-- | Convert bytes to a public key.
 toPublicKey :: ByteString -> Maybe PublicKey
 toPublicKey = sizedByteArray