diff --git a/Benchmark/Crypto.hs b/Benchmark/Crypto.hs
--- a/Benchmark/Crypto.hs
+++ b/Benchmark/Crypto.hs
@@ -60,6 +60,7 @@
 op f str = whnf (B.unpack . Ser.encode . f) str
 
 -- |Benchmark a block cipher by calling the 'ecb'' and 'unEcb'' functions
+-- on 128KB strings
 benchmarkBlockCipher :: BlockCipher k => k -> String -> Benchmark
 benchmarkBlockCipher k name =
 	let benchs = bgroup name [ bench "enc" (whnf (ecb' k) ps)
diff --git a/Crypto/Random.hs b/Crypto/Random.hs
--- a/Crypto/Random.hs
+++ b/Crypto/Random.hs
@@ -148,7 +148,7 @@
 
 instance CryptoRandomGen SystemRandom where
         newGen _ = Left NeedsInfiniteSeed
-        genSeedLength = Tagged 0
+        genSeedLength = Tagged maxBound
         genBytes req (SysRandom bs) =
                 let reqI = fromIntegral req
                     rnd = L.take reqI bs
@@ -159,7 +159,7 @@
         reseed _ _ = Left NeedsInfiniteSeed
         newGenIO = getSystemGen
 
--- | While the safety and wisdom of a splitting function depends on the properties of the generator being split,
+-- |While the safety and wisdom of a splitting function depends on the properties of the generator being split,
 -- several arguments from informed people indicate such a function is safe for NIST SP 800-90 generators.
 -- (see libraries@haskell.org discussion ~ Sept, Oct 2010)
 splitGen :: CryptoRandomGen g => g -> Either GenError (g,g)
diff --git a/Test/AES.hs b/Test/AES.hs
--- a/Test/AES.hs
+++ b/Test/AES.hs
@@ -17,6 +17,11 @@
 import Test.ParseNistKATs
 
 -- |Based on NIST KATs, build a list  of Tests for the instantiated AES algorithm.
+-- e.g. @runTests $ makeAESTests (undefined :: AES128)@
+--
+-- This is just a hack-job, if the BlockCipher instance doesn't toss keys
+-- of incorrect length then you'll get this test running, say, AES128 being tested
+-- with the first 128 bits of AES192 and AES256 tests.
 makeAESTests :: BlockCipher k => k -> IO [Test]
 makeAESTests k = do
         kats <- getAES_KATs k
@@ -73,7 +78,8 @@
         ct <- lookup "CIPHERTEXT" t
         pt <- lookup "PLAINTEXT" t
         k  <- lookup "KEY" t
-        let realKey = (fromJust . buildKey . hexStringToBS $ k) `asTypeOf` ek
+	rK <- (buildKey . hexStringToBS $ k)
+	let realKey = rK `asTypeOf` ek
             ctBS = hexStringToBS ct
             ptBS = hexStringToBS pt
 	    nm   = name ++ "-" ++ cnt
diff --git a/Test/Crypto.hs b/Test/Crypto.hs
--- a/Test/Crypto.hs
+++ b/Test/Crypto.hs
@@ -128,12 +128,20 @@
 
 -- |some generic blockcipher tests
 
+goodKey :: BlockCipher k => k -> B.ByteString -> Bool
 goodKey k bs =
-	case (buildKey bs `asTypeOf` Just k) of
+	case (getKey k bs `asTypeOf` Just k) of
 		Nothing -> False
 		Just _  -> True
 
-bKey k bs = let Just k' = (buildKey bs `asTypeOf` Just k) in k'
+bKey k bs = let Just k' = (getKey k bs `asTypeOf` Just k) in k'
+
+-- Pad out (or trim) material to correct length (for testing only!)
+getKey :: BlockCipher k => k -> B.ByteString -> Maybe k
+getKey k bs =
+	let l  = (keyLength `for` k) `div` 8
+	    b' = B.take l (B.concat $ replicate l (B.append bs (B.singleton 0)))
+	in buildKey b'
 
 bIV :: BlockCipher k => k -> B.ByteString -> Either String (IV k)
 bIV k bs = Ser.decode bs
diff --git a/crypto-api.cabal b/crypto-api.cabal
--- a/crypto-api.cabal
+++ b/crypto-api.cabal
@@ -1,5 +1,5 @@
 name:           crypto-api
-version:        0.5
+version:        0.5.2
 license:        BSD3
 license-file:   LICENSE
 copyright:      Thomas DuBuisson <thomas.dubuisson@gmail.com>
@@ -61,7 +61,7 @@
     extra-libraries: advapi32
   if flag(tests)
     exposed-modules: Test.Crypto, Test.AES, Test.SHA, Test.HMAC, Test.ParseNistKATs, Test.TwoFish
-    build-depends: QuickCheck >= 2.3 && < 2.4, directory >= 1.0.1.0 && < 1.2
+    build-depends: QuickCheck >= 2.3 && < 2.4, directory >= 1.0.1.0 && < 1.2, filepath
     other-modules: Paths_crypto_api
   if flag(benchmarks)
     exposed-modules: Benchmark.Crypto