2 files changed, 5 insertions, 3 deletions

diff --git a/src/Crypto/Macaroon/Verifier.hs b/src/Crypto/Macaroon/Verifier.hs
index a739437..4fc6aff 100644
--- a/src/Crypto/Macaroon/Verifier.hs
+++ b/src/Crypto/Macaroon/Verifier.hs
@@ -23,11 +23,13 @@ module Crypto.Macaroon.Verifier (
 ) where
 
 
-import           Control.Monad
+import           Control.Applicative
+import           Control.Monad hiding (forM)
 import           Control.Monad.IO.Class
 import           Data.Attoparsec.ByteString
 import           Data.Attoparsec.ByteString.Char8
 import           Data.Bool
+import           Data.Traversable
 import qualified Data.ByteString                  as BS
 import           Data.Either.Combinators
 
@@ -68,7 +70,7 @@ import           Crypto.Macaroon.Verifier.Internal
 -- caveat, parsed it and invalidated it;
 -- * 'Just' ('Right' '()') if the verifier has successfully verified the
 -- given caveat
-verify :: MonadIO m => Secret -> [Caveat -> m (Maybe (Either ValidationError ()))] -> Macaroon -> m (Either ValidationError Macaroon)
+verify :: (Functor m, MonadIO m) => Secret -> [Caveat -> m (Maybe (Either ValidationError ()))] -> Macaroon -> m (Either ValidationError Macaroon)
 verify secret verifiers m = join <$> forM (verifySig secret m) (verifyCavs verifiers)
 
 
diff --git a/src/Crypto/Macaroon/Verifier/Internal.hs b/src/Crypto/Macaroon/Verifier/Internal.hs
index 73eb66a..5126b2e 100644
--- a/src/Crypto/Macaroon/Verifier/Internal.hs
+++ b/src/Crypto/Macaroon/Verifier/Internal.hs
@@ -58,7 +58,7 @@ verifySig k m = bool (Left SigMismatch) (Right m) $
     derivedKey = toBytes (hmac "macaroons-key-generator" k :: HMAC SHA256)
 
 -- | Given a list of verifiers, verify each caveat of the given macaroon
-verifyCavs :: MonadIO m
+verifyCavs :: (Functor m, MonadIO m)
            => [Caveat -> m (Maybe (Either ValidationError ()))]
            -> Macaroon
            -> m (Either ValidationError Macaroon)