1 files changed, 4 insertions, 7 deletions

diff --git a/Data/OpenPGP.hs b/Data/OpenPGP.hs
index 74223b2..6667f1a 100644
--- a/Data/OpenPGP.hs
+++ b/Data/OpenPGP.hs
@@ -1005,9 +1005,7 @@ instance BINARY_CLASS MPI where
         put (MPI i)
                 | i >= 0 = do
                         put (bitl :: Word16)
-                        flip fix (B.length bytes - 1) $ \loop j -> do
-                                put (B.index bytes j)
-                                when (j /= 0) $ loop (j - 1)
+                        putSomeByteString bytes
                 | otherwise = fail $ "MPI is less than 0: " ++ show i
                 where
                 (bytes, bitl)
@@ -1015,16 +1013,15 @@ instance BINARY_CLASS MPI where
                         | otherwise     =
                                 (bytes', (fromIntegral (B.length bytes') - 1) * 8 + sigBit)
 
-                sigBit = fst $ until ((==0) . snd)
-                        (first (+1) . second (`shiftR` 1)) (0,B.last bytes)
-                bytes' = B.unfoldr (\x ->
+                sigBit = fromIntegral $ 8 - countLeadingZeros (B.index bytes 0)
+                bytes' = B.reverse $ B.unfoldr (\x ->
                                 if x == 0 then Nothing else
                                         Just (fromIntegral x, x `shiftR` 8)
                         ) i
         get = do
                 length <- fmap fromIntegral (get :: Get Word16)
                 bytes <- getSomeByteString =<< assertProp (>0) ((length + 7) `div` 8)
-                return $ MPI $ B.foldl (\a b -> (a `shiftL` 8) + fromIntegral b) 0 bytes
+                return $ MPI $ getBigNum (B.toStrict bytes)
 
 listUntilEnd :: (BINARY_CLASS a) => Get [a]
 listUntilEnd = do