diff --git a/benchs/Hash.hs b/benchs/Hash.hs
new file mode 100644
index 0000000..c0b5f03
--- /dev/null
+++ b/benchs/Hash.hs
@@ -0,0 +1,21 @@
+{-# LANGUAGE PackageImports #-}
+module Main where
+
+
+import System.Environment
+import qualified Data.ByteString.Lazy as L
+import "cryptonite" Crypto.Hash
+import qualified "cryptohash" Crypto.Hash as Old
+
+main = do
+    args <- getArgs
+    case args of
+        []        -> error "usage: bench <big-file>"
+        "old":x:_ -> do
+            r <- L.readFile x
+            let d = Old.hashlazy r :: Old.Digest Old.SHA1
+            putStrLn $ show d
+        x:_  -> do
+            r <- L.readFile x
+            let d = hashlazy r :: Digest SHA1
+            putStrLn $ show d