diff --git a/Crypto/Cipher/Blowfish/Box.hs b/Crypto/Cipher/Blowfish/Box.hs
index 65a6942..2a2f42c 100644
--- a/Crypto/Cipher/Blowfish/Box.hs
+++ b/Crypto/Cipher/Blowfish/Box.hs
@@ -3,39 +3,17 @@
 -- License     : BSD-style
 -- Stability   : experimental
 -- Portability : Good
+{-# LANGUAGE MagicHash #-}
 module Crypto.Cipher.Blowfish.Box
-    ( Pbox
-    , boxes
+    ( createKeySchedule
     ) where
 
-import Data.Bits
-import Data.Char (ord)
-import Data.Word
-import Data.Vector (Vector, (!), (//))
-import qualified Data.Vector as V
-import qualified Data.ByteString as B
+import Crypto.Internal.WordArray (mutableArray32FromAddrBE, MutableArray32)
 
-type Pbox = Vector Word32
-
-mkBox :: [Char] -> Vector Word32
-mkBox = V.fromList . map decode32be . doChunks 4 id . B.pack . map (fromIntegral . ord)
-
-doChunks :: Int -> (B.ByteString -> B.ByteString) -> B.ByteString -> [B.ByteString]
-doChunks n f b =
-    let (x, rest) = B.splitAt n b in
-    if B.length rest >= n
-        then f x : doChunks n f rest
-        else [ f x ]
-
-decode32be :: B.ByteString -> Word32
-decode32be s = id $!
-    (fromIntegral (s `B.index` 0) `shiftL` 24) .|.
-    (fromIntegral (s `B.index` 1) `shiftL` 16) .|.
-    (fromIntegral (s `B.index` 2) `shiftL`  8) .|.
-    (fromIntegral (s `B.index` 3) )
-
-boxes :: Pbox
-boxes = mkBox "\
+-- | Create a key schedule mutable array of the pbox followed by
+-- all the sboxes.
+createKeySchedule :: IO MutableArray32
+createKeySchedule = mutableArray32FromAddrBE 1042 "\
     \\x24\x3f\x6a\x88\x85\xa3\x08\xd3\x13\x19\x8a\x2e\x03\x70\x73\x44\
     \\xa4\x09\x38\x22\x29\x9f\x31\xd0\x08\x2e\xfa\x98\xec\x4e\x6c\x89\
     \\x45\x28\x21\xe6\x38\xd0\x13\x77\xbe\x54\x66\xcf\x34\xe9\x0c\x6c\
@@ -297,4 +275,4 @@ boxes = mkBox "\
     \\x19\x48\xc2\x5c\x02\xfb\x8a\x8c\x01\xc3\x6a\xe4\xd6\xeb\xe1\xf9\
     \\x90\xd4\xf8\x69\xa6\x5c\xde\xa0\x3f\x09\x25\x2d\xc2\x08\xe6\x9f\
     \\xb7\x4e\x61\x32\xce\x77\xe2\x5b\x57\x8f\xdf\xe3\x3a\xc3\x72\xe6\
-    \"
+    \"#
diff --git a/Crypto/Cipher/Blowfish/Primitive.hs b/Crypto/Cipher/Blowfish/Primitive.hs
index d09eb4f..f2b8cd8 100644
--- a/Crypto/Cipher/Blowfish/Primitive.hs
+++ b/Crypto/Cipher/Blowfish/Primitive.hs
@@ -19,9 +19,6 @@ module Crypto.Cipher.Blowfish.Primitive
     ) where
 
 import Control.Monad (forM_)
-import Data.Vector ((!))
-import qualified Data.Vector as V
-import qualified Data.Vector.Mutable as V (unsafeRead, unsafeWrite)
 import Data.Bits
 import Data.Word
 import qualified Data.ByteString as B
@@ -30,6 +27,7 @@ import Crypto.Error
 import Crypto.Internal.Compat
 import Crypto.Internal.ByteArray
 import Crypto.Internal.Words
+import Crypto.Internal.WordArray
 import Crypto.Cipher.Blowfish.Box
 
 -- | variable keyed blowfish state
@@ -96,17 +94,15 @@ coreCrypto (BF p s0 s1 s2 s3) input = doRound input 0
 makeKeySchedule :: [Word32] -> Context
 makeKeySchedule key =
     let v = unsafeDoIO $ do
-              mv <- V.thaw boxes
-              forM_ (zip key [0..17]) $ \(k, i) ->
-                  V.unsafeRead mv i >>= \pVal -> V.unsafeWrite mv i (k `xor` pVal)
-                  --mutableArrayWriteXor32 mv i k
+              mv <- createKeySchedule
+              forM_ (zip key [0..17]) $ \(k, i) -> mutableArrayWriteXor32 mv i k
               prepare mv
-              V.unsafeFreeze mv
-     in BF (V.slice 0 18 v !)
-           (V.slice s0 256 v !)
-           (V.slice s1 256 v !)
-           (V.slice s2 256 v !)
-           (V.slice s3 256 v !)
+              mutableArray32Freeze mv
+     in BF (\i -> arrayRead32 v i)
+           (\i -> arrayRead32 v (s0+i))
+           (\i -> arrayRead32 v (s1+i))
+           (\i -> arrayRead32 v (s2+i))
+           (\i -> arrayRead32 v (s3+i))
   where
         s0 = 18
         s1 = 274
@@ -119,20 +115,20 @@ makeKeySchedule key =
                   | otherwise = do
                       ninput <- coreCryptoMutable input
                       let (nl, nr) = w64to32 ninput
-                      V.unsafeWrite mctx i     nl
-                      V.unsafeWrite mctx (i+1) nr
+                      mutableArrayWrite32 mctx i     nl
+                      mutableArrayWrite32 mctx (i+1) nr
                       loop (i+2) ninput
 
                 coreCryptoMutable :: Word64 -> IO Word64
                 coreCryptoMutable input = doRound input 0
                   where doRound i roundIndex
                           | roundIndex == 16 = do
-                              pVal1 <- V.unsafeRead mctx 16
-                              pVal2 <- V.unsafeRead mctx 17
+                              pVal1 <- mutableArrayRead32 mctx 16
+                              pVal2 <- mutableArrayRead32 mctx 17
                               let final = (fromIntegral pVal1 `shiftL` 32) .|. fromIntegral pVal2
                               return $ rotateL (i `xor` final) 32
                           | otherwise     = do
-                              pVal <- V.unsafeRead mctx roundIndex
+                              pVal <- mutableArrayRead32 mctx roundIndex
                               let newr = fromIntegral (i `shiftR` 32) `xor` pVal
                               newr' <- f newr
                               let newi = ((i `shiftL` 32) `xor` newr') .|. (fromIntegral newr)
@@ -140,8 +136,8 @@ makeKeySchedule key =
 
 
                 f   :: Word32 -> IO Word64
-                f t = do a <- V.unsafeRead mctx (s0 + fromIntegral ((t `shiftR` 24) .&. 0xff))
-                         b <- V.unsafeRead mctx (s1 + fromIntegral ((t `shiftR` 16) .&. 0xff))
-                         c <- V.unsafeRead mctx (s2 + fromIntegral ((t `shiftR` 8) .&. 0xff))
-                         d <- V.unsafeRead mctx (s3 + fromIntegral (t .&. 0xff))
+                f t = do a <- mutableArrayRead32 mctx (s0 + fromIntegral ((t `shiftR` 24) .&. 0xff))
+                         b <- mutableArrayRead32 mctx (s1 + fromIntegral ((t `shiftR` 16) .&. 0xff))
+                         c <- mutableArrayRead32 mctx (s2 + fromIntegral ((t `shiftR` 8) .&. 0xff))
+                         d <- mutableArrayRead32 mctx (s3 + fromIntegral (t .&. 0xff))
                          return (fromIntegral (((a + b) `xor` c) + d) `shiftL` 32)