diff --git a/clientsession.cabal b/clientsession.cabal
--- a/clientsession.cabal
+++ b/clientsession.cabal
@@ -1,5 +1,5 @@
 name:            clientsession
-version:         0.7.4.3
+version:         0.7.5
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>, Felipe Lessa <felipe.lessa@gmail.com>
@@ -26,7 +26,7 @@
                    , cereal              >= 0.3        && < 0.4
                    , directory           >= 1          && < 1.2
                    , tagged              >= 0.1
-                   , crypto-api          >= 0.6.4      && < 0.11
+                   , crypto-api          >= 0.8        && < 0.11
                    , cryptocipher        >= 0.2.5
                    , skein               >= 0.1        && < 0.2
                    , base64-bytestring   >= 0.1.1.1    && < 0.2
diff --git a/src/Web/ClientSession.hs b/src/Web/ClientSession.hs
--- a/src/Web/ClientSession.hs
+++ b/src/Web/ClientSession.hs
@@ -54,8 +54,6 @@
 
 -- from base
 import Control.Monad (guard, when)
-import Data.Bits ((.|.), xor)
-import Data.List (foldl')
 import qualified Data.IORef as I
 import System.IO.Unsafe (unsafePerformIO)
 import Control.Concurrent (forkIO)
@@ -74,7 +72,7 @@
 import Data.Tagged (Tagged, untag)
 
 -- from crypto-api
-import Crypto.Classes (buildKey)
+import Crypto.Classes (buildKey, constTimeEq)
 import Crypto.Random (genSeedLength, reseed)
 import Crypto.Types (ByteLength)
 import qualified Crypto.Modes as Modes
@@ -208,18 +206,11 @@
     guard (S.length dataBS >= 48) -- 16 bytes of IV + 32 bytes of Skein-MAC-512-256
     let (auth, toBeAuthed) = S.splitAt 32 dataBS
         auth' = macKey key toBeAuthed
-    guard (encode auth' `compareHash` auth)
+    guard (encode auth' `constTimeEq` auth)
     let (iv_e, encrypted) = S.splitAt 16 toBeAuthed
     iv <- either (const Nothing) Just $ decode iv_e
     let (x, _) = Modes.unCtr' Modes.incIV (aesKey key) iv encrypted
     return x
-
--- | Compare two bytestrings.  Always takes the same ammount of
--- time, avoiding timing attacks.
-compareHash :: S.ByteString -> S.ByteString -> Bool
-compareHash s1 s2 =
-    S.length s1 == S.length s2 &&
-    foldl' (.|.) 0 (S.zipWith xor s1 s2) == 0
 
 -- Significantly more efficient random IV generation. Initial
 -- benchmarks placed it at 6.06 us versus 1.69 ms for Modes.getIVIO,