diff --git a/src/Diff.hs b/src/Diff.hs
index dbc2379..45bc5c7 100644
--- a/src/Diff.hs
+++ b/src/Diff.hs
@@ -16,7 +16,6 @@ import Data.List (groupBy, mapAccumL)
 import Data.List.Extra (split, takeEnd)
 import qualified Data.Vector as V
 import qualified Data.Vector.Unboxed.Mutable as M
-import Debug.Trace
 import Substr
 import Types
 
@@ -36,8 +35,7 @@ data DiffEnv =
     }
   deriving (Show)
 
-toksMatch x y DiffEnv {deT1 = t1, deT2 = t2} =
-  t1 V.! x == t2 V.! y
+toksMatch x y DiffEnv {deT1 = t1, deT2 = t2} = t1 V.! x == t2 V.! y
 
 stripEqToks :: TV -> TV -> (Diff, Diff, TV, TV)
 stripEqToks t1 t2 = (pre, post, t1', t2')
@@ -50,7 +48,7 @@ stripEqToks t1 t2 = (pre, post, t1', t2')
     b = firstDiff 0
     lastDiff i
       | l1 - i - 1 >= b &&
-          l2 - i - 1 >= b && t1 V.! (l1 - i - 1) == t2 V.! (l2 - i - 1)=
+          l2 - i - 1 >= b && t1 V.! (l1 - i - 1) == t2 V.! (l2 - i - 1) =
         lastDiff (i + 1)
       | otherwise = i
     e = lastDiff 0
@@ -117,7 +115,7 @@ diffToks' :: DiffEnv -> Diff
 diffToks' de@DiffEnv {deS = s, deE = e, deA = a, deB = b, deTrans = trans} =
   diff
   where
-    mid = (s + e) `div` 2
+    mid = quot (s + e) 2
     vecSmid = vecS mid
     vecEmid = vecE mid
     extraScore i =
@@ -263,12 +261,23 @@ diffToks' de@DiffEnv {deS = s, deE = e, deA = a, deB = b, deTrans = trans} =
         diffToks' de {deS = mid, deVS = vecSmid, deA = opt}
 
 hunks :: Int -> Diff -> [Hunk]
-hunks ctxt =
-  map (stripNums . concat) .
-  split null .
-  concat . check . map breakKeeps . groupBy ((==) `on` fst . snd) . addNums
+hunks ctxt d =
+  map (stripNums . map snd) .
+  filter (not . null) . split fst . zip remove . addNums $
+  d
   where
+    edit (Keep, _) = 0
+    edit _ = 1
+    edits :: [Int]
+    edits = tail $ scanl (+) 0 (map edit d)
+    padEnd _ [] = []
+    padEnd i [a] = replicate i a
+    padEnd i (x:xs) = x : padEnd i xs
+    remove =
+      drop ctxt $
+      zipWith (<=) (padEnd ctxt edits) (replicate (1 + 2 * ctxt) 0 ++ edits)
     addNums = snd . mapAccumL countTok (0, 0)
+    stripNums = (,) <$> fst . head <*> map snd
     countTok x@(i, j) d@(op, _) =
       (,)
         (case op of
@@ -276,17 +285,3 @@ hunks ctxt =
            Keep -> (i + 1, j + 1)
            Add -> (i, j + 1))
         (x, d)
-    stripNums = (,) <$> fst . head <*> map snd
-    breakKeeps ks@((_, (Keep, _)):_) =
-      let (a, b') = splitAt ctxt ks
-          (b, c) = splitAt ctxt b'
-       in if null c
-            then [ks]
-            else [a, [], takeEnd ctxt b']
-    breakKeeps a = [a]
-    check ([_, [], _]:[]) = []
-    check ([_, [], a]:xs) = [a] : checkLast xs
-    check a = checkLast a
-    checkLast [] = []
-    checkLast ([a, [], _]:[]) = [[a]]
-    checkLast (a:xs) = a:checkLast xs
diff --git a/src/Format.hs b/src/Format.hs
index d4f4308..b69a624 100644
--- a/src/Format.hs
+++ b/src/Format.hs
@@ -11,21 +11,18 @@ import qualified Data.ByteString.Lazy as BL
 import Data.String
 import Substr
 
-pprHunkHdr i j = fromString $ "@@ -" ++ show i ++ " +" ++ show j ++ " @@"
+pprHunkHdr i j = fromString $ "@@ -" ++ show i ++ " +" ++ show j ++ " @@" 
 
 lineSep = fromString "\n"
 
+pprHunks :: [Hunk] -> BS
+pprHunks = B.concat . map pprHunk
+
 pprHunk :: Hunk -> BS
-pprHunk ((i, j), toks) =
-  B.intercalate lineSep (pprHunkHdr i j : pprDiff toks)
-
-pprHunks = B.intercalate lineSep . map pprHunk
-
-pprDiff :: Diff -> [BS]
-pprDiff = map pprDiff1
+pprHunk ((i, j), toks) = B.concat ((pprHunkHdr i j <> lineSep) : map pprDiff1 toks)
 
 pprDiff1 (op, (tok, s)) =
-  fromString pfx <> escNewlines s
+  fromString pfx <> escNewlines s <> lineSep
   where
     pfx =
       case (op, tok) of
diff --git a/src/Main.hs b/src/Main.hs
index c561a35..9faad08 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -114,5 +114,5 @@ main =
              toks1 <- V.fromList <$> redfaTokenize redfa data1
              toks2 <- V.fromList <$> redfaTokenize redfa data2
              let hs = hunks (max 0 ctxt) $ diffToks toks1 toks2
-             B8.putStrLn $ pprHunks hs
+             B8.putStr $ pprHunks hs
            CmdPatch {} -> putStrLn "not supported yet"