diff --git a/Annex/DirHashes.hs b/Annex/DirHashes.hs
index 194b4932c5..1e1991364a 100644
--- a/Annex/DirHashes.hs
+++ b/Annex/DirHashes.hs
@@ -65,14 +65,14 @@ hashDirs (HashLevels 1) sz s = addTrailingPathSeparator $ take sz s
 hashDirs _ sz s = addTrailingPathSeparator $ take sz s </> drop sz s
 
 hashDirLower :: HashLevels -> Hasher
-hashDirLower n k = hashDirs n 3 $ take 6 $ show $ md5 $ serializeKey' $ nonChunkKey k
+hashDirLower n k = hashDirs n 3 $ take 6 $ show $ md5s $ serializeKey' $ nonChunkKey k
 
 {- This was originally using Data.Hash.MD5 from MissingH. This new version
 - is faster, but ugly as it has to replicate the 4 Word32's that produced. -}
 hashDirMixed :: HashLevels -> Hasher
 hashDirMixed n k = hashDirs n 2 $ take 4 $ concatMap display_32bits_as_dir $
 	encodeWord32 $ map fromIntegral $ Data.ByteArray.unpack $
-		Utility.Hash.md5 $ serializeKey' $ nonChunkKey k
+		Utility.Hash.md5s $ serializeKey' $ nonChunkKey k
   where
 	encodeWord32 (b1:b2:b3:b4:rest) =
 		(shiftL b4 24 .|. shiftL b3 16 .|. shiftL b2 8 .|. b1)
diff --git a/Annex/Locations.hs b/Annex/Locations.hs
index a45fa02c21..32113d94a1 100644
--- a/Annex/Locations.hs
+++ b/Annex/Locations.hs
@@ -515,7 +515,7 @@ keyFile :: Key -> FilePath
 keyFile = fromRawFilePath . keyFile'
 
 keyFile' :: Key -> RawFilePath
-keyFile' = S8.concatMap esc . L.toStrict . serializeKey'
+keyFile' = S8.concatMap esc . serializeKey'
   where
 	esc '&' = "&a"
 	esc '%' = "&s"
diff --git a/Annex/VariantFile.hs b/Annex/VariantFile.hs
index acab1e8281..9808293be9 100644
--- a/Annex/VariantFile.hs
+++ b/Annex/VariantFile.hs
@@ -10,7 +10,7 @@ module Annex.VariantFile where
 import Annex.Common
 import Utility.Hash
 
-import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString as S
 
 variantMarker :: String
 variantMarker = ".variant-"
@@ -41,5 +41,5 @@ variantFile file key
   where
 	doubleconflict = variantMarker `isInfixOf` file
 
-shortHash :: L.ByteString -> String
-shortHash = take 4 . show . md5
+shortHash :: S.ByteString -> String
+shortHash = take 4 . show . md5s
diff --git a/Key.hs b/Key.hs
index eaa179d9f4..16f56e4185 100644
--- a/Key.hs
+++ b/Key.hs
@@ -56,11 +56,13 @@ stubKey = Key
 
 -- Gets the parent of a chunk key.
 nonChunkKey :: Key -> Key
-nonChunkKey k = k
-	{ keyChunkSize = Nothing
-	, keyChunkNum = Nothing
-	, keySerialization = Nothing
-	}
+nonChunkKey k
+	| keyChunkSize k == Nothing && keyChunkNum k == Nothing = k
+	| otherwise = k
+		{ keyChunkSize = Nothing
+		, keyChunkNum = Nothing
+		, keySerialization = Nothing
+		}
 
 -- Where a chunk key is offset within its parent.
 chunkKeyOffset :: Key -> Maybe Integer
@@ -96,12 +98,13 @@ buildKey k = byteString (formatKeyVariety (keyVariety k))
 	_ ?: Nothing = mempty
 
 serializeKey :: Key -> String
-serializeKey = decodeBL' . serializeKey'
+serializeKey = decodeBS' . serializeKey'
 
-serializeKey' :: Key -> L.ByteString
+serializeKey' :: Key -> S.ByteString
 serializeKey' k = case keySerialization k of
-	Nothing -> toLazyByteStringWith (safeStrategy 128 smallChunkSize) L.empty (buildKey k)
-	Just b -> L.fromStrict b
+	Nothing -> L.toStrict $
+		toLazyByteStringWith (safeStrategy 128 smallChunkSize) L.empty (buildKey k)
+	Just b -> b
 
 {- This is a strict parser for security reasons; a key
  - can contain only 4 fields, which all consist only of numbers.
diff --git a/Utility/Hash.hs b/Utility/Hash.hs
index 3bbb0627b7..d422c0bd53 100644
--- a/Utility/Hash.hs
+++ b/Utility/Hash.hs
@@ -27,12 +27,14 @@ module Utility.Hash (
 	blake2b_512,
 #endif
 	md5,
+	md5s,
 	prop_hashes_stable,
 	Mac(..),
 	calcMac,
 	prop_mac_stable,
 ) where
 
+import qualified Data.ByteString as S
 import qualified Data.ByteString.Lazy as L
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
@@ -112,6 +114,9 @@ blake2b_512 = hashlazy
 md5 ::  L.ByteString -> Digest MD5
 md5 = hashlazy
 
+md5s ::  S.ByteString -> Digest MD5
+md5s = hash
+
 {- Check that all the hashes continue to hash the same. -}
 prop_hashes_stable :: Bool
 prop_hashes_stable = all (\(hasher, result) -> hasher foo == result)