diff --git a/persona.cabal b/persona.cabal
--- a/persona.cabal
+++ b/persona.cabal
@@ -1,5 +1,5 @@
 name:                persona
-version:             0.1.0.0
+version:             0.2.0.0
 synopsis:            Persona (BrowserID) library
 description:         Persona (BrowesrID) library
 homepage:            https://github.com/frasertweedale/hs-persona
@@ -10,7 +10,7 @@
   README.md
 author:              Fraser Tweedale
 maintainer:          frase@frase.id.au
-copyright:           Copyright (C) 2013, 2014  Fraser Tweedale
+copyright:           Copyright (C) 2013, 2014, 2015  Fraser Tweedale
 category:            Web
 build-type:          Simple
 cabal-version:       >=1.10
@@ -34,7 +34,7 @@
     , text >= 0.11
     , time >= 1.4
     , unordered-containers >= 0.2
-    , jose >= 0.3.38.0
+    , jose >= 0.4
 
   exposed-modules:
     Crypto.Persona
diff --git a/src/Crypto/Persona.hs b/src/Crypto/Persona.hs
--- a/src/Crypto/Persona.hs
+++ b/src/Crypto/Persona.hs
@@ -1,5 +1,5 @@
 -- This file is part of persona - Persona (BrowserID) library
--- Copyright (C) 2013, 2014  Fraser Tweedale
+-- Copyright (C) 2013, 2014, 2015, 2016  Fraser Tweedale
 --
 -- persona is free software: you can redistribute it and/or modify
 -- it under the terms of the GNU Affero General Public License as published by
@@ -48,7 +48,7 @@
 
 import Control.Applicative
 
-import Control.Lens hiding ((.=))
+import Control.Lens hiding (iat, (.=))
 import Data.Aeson
 import Data.Default.Class (def)
 import qualified Data.Text as T
@@ -83,7 +83,7 @@
 
 -- | Basic /support document/.
 --
--- See https://developer.mozilla.org/en-US/Persona/.well-known-browserid.
+-- See <https://developer.mozilla.org/en-US/Persona/.well-known-browserid>.
 --
 data SupportDocument = SupportDocument
     { _publicKey       :: JWK'
@@ -113,7 +113,8 @@
 -- a move to the JSON Web Key (JWK) format.
 --
 supportDocument :: JWK' -> RelativeURI -> RelativeURI -> Maybe SupportDocument
-supportDocument k a p = publicKey public $ SupportDocument k a p
+supportDocument k a p =
+  SupportDocument k a p & publicKey (preview asPublicKey)
 
 
 -- | /Delegated support document/
@@ -150,9 +151,8 @@
 -- | Create an identity assertion.
 --
 certify
-  :: CPRG g
-  => g
-  -> JWK'         -- ^ Signing key
+  :: MonadRandom m
+  => JWK'         -- ^ Signing key
   -> StringOrURI  -- ^ Issuer
   -> UTCTime
   -- ^ Current time.  Will be used for the "iat" claim and in the
@@ -162,9 +162,9 @@
   -- "exp" claim.
   -> Value        -- ^ User public key object
   -> Principal    -- ^ Principal
-  -> (Either Error JWT, g)
-certify g k iss t dur pk principal =
-  createJWSJWT g (toJWK k) header claims
+  -> m (Either Error JWT)
+certify k iss t dur pk principal =
+  createJWSJWT (toJWK k) header claims
   where
   claims = emptyClaimsSet
     & claimIss .~ Just iss