diff --git a/hw-bits.cabal b/hw-bits.cabal
--- a/hw-bits.cabal
+++ b/hw-bits.cabal
@@ -1,5 +1,5 @@
 name:                   hw-bits
-version:                0.0.0.10
+version:                0.0.0.11
 synopsis:               Conduits for tokenizing streams.
 description:            Please see README.md
 homepage:               http://github.com/haskell-works/hw-bits#readme
@@ -46,6 +46,7 @@
                       , HaskellWorks.Data.Bits.PopCount.PopCount1
                       , HaskellWorks.Data.Bits.Types.Broadword
                       , HaskellWorks.Data.Bits.Types.Builtin
+                      , HaskellWorks.Data.Bits.Unmatched
                       , HaskellWorks.Data.Bits.Word
   build-depends:        base                          >= 4          && < 5
                       , bytestring
@@ -63,6 +64,7 @@
   other-modules:        HaskellWorks.Data.Bits.BitReadSpec
                       , HaskellWorks.Data.Bits.BitWiseSpec
                       , HaskellWorks.Data.Bits.FromBitTextByteStringSpec
+                      , HaskellWorks.Data.Bits.UnmatchedSpec
   build-depends:        base                          >= 4          && < 5
                       , bytestring
                       , hspec
diff --git a/src/HaskellWorks/Data/Bits/Unmatched.hs b/src/HaskellWorks/Data/Bits/Unmatched.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/Bits/Unmatched.hs
@@ -0,0 +1,206 @@
+{-# LANGUAGE FlexibleInstances #-}
+
+module HaskellWorks.Data.Bits.Unmatched
+  ( UnmatchedL0(..)
+  , UnmatchedL1(..)
+  , UnmatchedR0(..)
+  , UnmatchedR1(..)
+  ) where
+
+import qualified Data.Vector.Storable               as DVS
+import           Data.Word
+import           HaskellWorks.Data.Bits.FixedBitSize
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.Positioning
+
+bitEnd :: FixedBitSize w => w -> Position
+bitEnd = toPosition . fixedBitSize
+{-# INLINE bitEnd #-}
+
+goL0 :: (TestBit w, FixedBitSize w) => Position -> Int -> w -> Int
+goL0 n c w = if 0 <= n && n < bitEnd w
+  then let delta = if w .?. (bitEnd w - n - 1) then -1 else 1 in goL0 (n + 1) ((c + delta) `max` 0) w
+  else c
+{-# INLINE goL0 #-}
+
+goL1 :: (TestBit w, FixedBitSize w) => Position -> Int -> w -> Int
+goL1 n c w = if 0 <= n && n < bitEnd w
+  then let delta = if w .?. (bitEnd w - n - 1) then 1 else -1 in goL1 (n + 1) ((c + delta) `max` 0) w
+  else c
+{-# INLINE goL1 #-}
+
+goR0 :: (TestBit w, FixedBitSize w) => Position -> Int -> w -> Int
+goR0 n c w = if 0 <= n && n < bitEnd w
+  then let delta = if w .?. n then -1 else 1 in goR0 (n + 1) ((c + delta) `max` 0) w
+  else c
+{-# INLINE goR0 #-}
+
+goR1 :: (TestBit w, FixedBitSize w) => Position -> Int -> w -> Int
+goR1 n c w = if 0 <= n && n < bitEnd w
+  then let delta = if w .?. n then 1 else -1 in goR1 (n + 1) ((c + delta) `max` 0) w
+  else c
+{-# INLINE goR1 #-}
+
+goDVSL0 :: (UnmatchedL0 w, UnmatchedR1 w, DVS.Storable w) => Int -> DVS.Vector w -> Int
+goDVSL0 ub v = if DVS.length v == 0
+  then ub
+  else let a = DVS.last v in goDVSL0 (unmatchedL0 a + ((ub - unmatchedR1 a) `max` 0)) (DVS.init v)
+{-# INLINE goDVSL0 #-}
+
+goDVSL1 :: (UnmatchedL1 w, UnmatchedR0 w, DVS.Storable w) => Int -> DVS.Vector w -> Int
+goDVSL1 ub v = if DVS.length v == 0
+  then ub
+  else let a = DVS.last v in goDVSL1 (unmatchedL1 a + ((ub - unmatchedR0 a) `max` 0)) (DVS.init v)
+{-# INLINE goDVSL1 #-}
+
+goDVSR0 :: (UnmatchedR0 w, UnmatchedL1 w, DVS.Storable w) => Int -> DVS.Vector w -> Int
+goDVSR0 ua v = if DVS.length v == 0
+  then ua
+  else let b = DVS.head v in goDVSR0 (unmatchedR0 b + ((ua - unmatchedL1 b) `max` 0)) (DVS.tail v)
+{-# INLINE goDVSR0 #-}
+
+goDVSR1 :: (UnmatchedR1 w, UnmatchedL0 w, DVS.Storable w) => Int -> DVS.Vector w -> Int
+goDVSR1 ub v = if DVS.length v == 0
+  then ub
+  else let a = DVS.head v in goDVSR1 (unmatchedR1 a + ((ub - unmatchedL0 a) `max` 0)) (DVS.tail v)
+{-# INLINE goDVSR1 #-}
+
+class UnmatchedL0 a where
+  unmatchedL0 :: a -> Int
+
+class UnmatchedL1 a where
+  unmatchedL1 :: a -> Int
+
+class UnmatchedR0 a where
+  unmatchedR0 :: a -> Int
+
+class UnmatchedR1 a where
+  unmatchedR1 :: a -> Int
+
+instance UnmatchedL0 Word8 where
+  unmatchedL0 = goL0 0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 Word16 where
+  unmatchedL0 = goL0 0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 Word32 where
+  unmatchedL0 = goL0 0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 Word64 where
+  unmatchedL0 = goL0 0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 (DVS.Vector Word8) where
+  unmatchedL0 = goDVSL0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 (DVS.Vector Word16) where
+  unmatchedL0 = goDVSL0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 (DVS.Vector Word32) where
+  unmatchedL0 = goDVSL0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL0 (DVS.Vector Word64) where
+  unmatchedL0 = goDVSL0 0
+  {-# INLINE unmatchedL0 #-}
+
+instance UnmatchedL1 Word8 where
+  unmatchedL1 = goL1 0 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 Word16 where
+  unmatchedL1 = goL1 0 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 Word32 where
+  unmatchedL1 = goL1 0 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 Word64 where
+  unmatchedL1 = goL1 0 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 (DVS.Vector Word8) where
+  unmatchedL1 = goDVSL1 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 (DVS.Vector Word16) where
+  unmatchedL1 = goDVSL1 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 (DVS.Vector Word32) where
+  unmatchedL1 = goDVSL1 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedL1 (DVS.Vector Word64) where
+  unmatchedL1 = goDVSL1 0
+  {-# INLINE unmatchedL1 #-}
+
+instance UnmatchedR0 Word8 where
+  unmatchedR0 = goR0 0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 Word16 where
+  unmatchedR0 = goR0 0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 Word32 where
+  unmatchedR0 = goR0 0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 Word64 where
+  unmatchedR0 = goR0 0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 (DVS.Vector Word8) where
+  unmatchedR0 = goDVSR0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 (DVS.Vector Word16) where
+  unmatchedR0 = goDVSR0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 (DVS.Vector Word32) where
+  unmatchedR0 = goDVSR0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR0 (DVS.Vector Word64) where
+  unmatchedR0 = goDVSR0 0
+  {-# INLINE unmatchedR0 #-}
+
+instance UnmatchedR1 Word8 where
+  unmatchedR1 = goR1 0 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 Word16 where
+  unmatchedR1 = goR1 0 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 Word32 where
+  unmatchedR1 = goR1 0 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 Word64 where
+  unmatchedR1 = goR1 0 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 (DVS.Vector Word8) where
+  unmatchedR1 = goDVSR1 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 (DVS.Vector Word16) where
+  unmatchedR1 = goDVSR1 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 (DVS.Vector Word32) where
+  unmatchedR1 = goDVSR1 0
+  {-# INLINE unmatchedR1 #-}
+
+instance UnmatchedR1 (DVS.Vector Word64) where
+  unmatchedR1 = goDVSR1 0
+  {-# INLINE unmatchedR1 #-}
diff --git a/test/HaskellWorks/Data/Bits/BitWiseSpec.hs b/test/HaskellWorks/Data/Bits/BitWiseSpec.hs
--- a/test/HaskellWorks/Data/Bits/BitWiseSpec.hs
+++ b/test/HaskellWorks/Data/Bits/BitWiseSpec.hs
@@ -15,7 +15,7 @@
 {-# ANN module ("HLint: ignore Redundant do" :: String) #-}
 
 spec :: Spec
-spec = describe "HaskellWorks.Data.SuccinctSpec" $ do
+spec = describe "HaskellWorks.Data.Bits.BitWiseSpec" $ do
   describe "for popCount0" $ do
     it "for Word8 matches Data.Bits implementation" $ property $
       \(w :: Word8 ) -> popCount0 w == bitLength w - fromIntegral (B.popCount w)
diff --git a/test/HaskellWorks/Data/Bits/FromBitTextByteStringSpec.hs b/test/HaskellWorks/Data/Bits/FromBitTextByteStringSpec.hs
--- a/test/HaskellWorks/Data/Bits/FromBitTextByteStringSpec.hs
+++ b/test/HaskellWorks/Data/Bits/FromBitTextByteStringSpec.hs
@@ -15,7 +15,7 @@
 {-# ANN module ("HLint: Ignore Redundant do" :: String) #-}
 
 spec :: Spec
-spec = describe "HaskellWorks.Data.FromBitTextByteStringSpec" $ do
+spec = describe "HaskellWorks.Data.Bits.FromBitTextByteStringSpec" $ do
   describe "For (DVS.Vector Word8)" $ do
     it "fromBitTextByteString (BS.unpack []) :: DVS.Vector Word8" $
       let w = fromBitTextByteString (BS.pack []) ::DVS.Vector Word8 in
diff --git a/test/HaskellWorks/Data/Bits/UnmatchedSpec.hs b/test/HaskellWorks/Data/Bits/UnmatchedSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/HaskellWorks/Data/Bits/UnmatchedSpec.hs
@@ -0,0 +1,88 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module HaskellWorks.Data.Bits.UnmatchedSpec (spec) where
+
+import           Data.Vector.Storable                 as DVS
+import           Data.Word
+import           HaskellWorks.Data.Bits.BitWise
+import           HaskellWorks.Data.Bits.FixedBitSize
+import           HaskellWorks.Data.Bits.Unmatched
+import           Test.Hspec
+import           Test.QuickCheck
+
+{-# ANN module ("HLint: Ignore Redundant do" :: String) #-}
+
+spec :: Spec
+spec = describe "HaskellWorks.Data.Bits.UnmatchedSpec" $ do
+  describe "For Word8" $ do
+    it "umatchedL0 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL0 a + ((unmatchedL0 b - unmatchedR1 a) `max` 0) `shouldBe` unmatchedL0 c
+    it "umatchedL1 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL1 a + ((unmatchedL1 b - unmatchedR0 a) `max` 0) `shouldBe` unmatchedL1 c
+    it "umatchedR0 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR0 b + ((unmatchedR0 a - unmatchedL1 b) `max` 0) `shouldBe` unmatchedR0 c
+    it "umatchedR1 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR1 b + ((unmatchedR1 a - unmatchedL0 b) `max` 0) `shouldBe` unmatchedR1 c
+  describe "For Word16" $ do
+    it "umatchedL0 concatentation" $
+      property $ \(a :: Word16) (b :: Word16) ->
+        let c :: Word32 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL0 a + ((unmatchedL0 b - unmatchedR1 a) `max` 0) `shouldBe` unmatchedL0 c
+    it "umatchedL1 concatentation" $
+      property $ \(a :: Word16) (b :: Word16) ->
+        let c :: Word32 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL1 a + ((unmatchedL1 b - unmatchedR0 a) `max` 0) `shouldBe` unmatchedL1 c
+    it "umatchedR0 concatentation" $
+      property $ \(a :: Word16) (b :: Word16) ->
+        let c :: Word32 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR0 b + ((unmatchedR0 a - unmatchedL1 b) `max` 0) `shouldBe` unmatchedR0 c
+    it "umatchedR1 concatentation" $
+      property $ \(a :: Word16) (b :: Word16) ->
+        let c :: Word32 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR1 b + ((unmatchedR1 a - unmatchedL0 b) `max` 0) `shouldBe` unmatchedR1 c
+  describe "For Word32" $ do
+    it "umatchedL0 concatentation" $
+      property $ \(a :: Word32) (b :: Word32) ->
+        let c :: Word64 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL0 a + ((unmatchedL0 b - unmatchedR1 a) `max` 0) `shouldBe` unmatchedL0 c
+    it "umatchedL1 concatentation" $
+      property $ \(a :: Word32) (b :: Word32) ->
+        let c :: Word64 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL1 a + ((unmatchedL1 b - unmatchedR0 a) `max` 0) `shouldBe` unmatchedL1 c
+    it "umatchedR0 concatentation" $
+      property $ \(a :: Word32) (b :: Word32) ->
+        let c :: Word64 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR0 b + ((unmatchedR0 a - unmatchedL1 b) `max` 0) `shouldBe` unmatchedR0 c
+    it "umatchedR1 concatentation" $
+      property $ \(a :: Word32) (b :: Word32) ->
+        let c :: Word64 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR1 b + ((unmatchedR1 a - unmatchedL0 b) `max` 0) `shouldBe` unmatchedR1 c
+  describe "For (DVS.Vector Word8)" $ do
+    it "umatchedL0 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c = DVS.fromList [a, b] in
+        let d :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL0 d `shouldBe` unmatchedL0 c
+    it "umatchedL1 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c = DVS.fromList [a, b] in
+        let d :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedL1 d `shouldBe` unmatchedL1 c
+    it "umatchedR0 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c = DVS.fromList [a, b] in
+        let d :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR0 d `shouldBe` unmatchedR0 c
+    it "umatchedR1 concatentation" $
+      property $ \(a :: Word8) (b :: Word8) ->
+        let c = DVS.fromList [a, b] in
+        let d :: Word16 = (fromIntegral a) .|. (fromIntegral b .<. fixedBitSize b) in
+        unmatchedR1 d `shouldBe` unmatchedR1 c