diff --git a/Network/ByteOrder.hs b/Network/ByteOrder.hs
--- a/Network/ByteOrder.hs
+++ b/Network/ByteOrder.hs
@@ -85,6 +85,7 @@
 import System.IO.Unsafe (unsafeDupablePerformIO)
 
 -- $setup
+-- >>> :set -XOverloadedStrings
 -- >>> import Data.ByteString hiding (foldl')
 -- >>> import Data.Word
 -- >>> import Data.List
@@ -426,7 +427,7 @@
 -- | Write three bytes and ff one byte.
 --   If buffer overrun occurs, 'BufferOverrun' is thrown.
 --
--- >>> withWriteBuffer 3 $ \wbuf -> write24 wbuf (65 * 256^2 + 66 * 256 + 67)
+-- >>> withWriteBuffer 3 $ \wbuf -> write24 wbuf (65 * 256^(2 :: Int) + 66 * 256 + 67)
 -- "ABC"
 write24 :: WriteBuffer -> Word32 -> IO ()
 write24 WriteBuffer{..} w = do
@@ -440,7 +441,7 @@
 -- | Write four bytes and ff one byte.
 --   If buffer overrun occurs, 'BufferOverrun' is thrown.
 --
--- >>> withWriteBuffer 4 $ \wbuf -> write32 wbuf (65 * 256^3 + 66 * 256^2 + 67 * 256 + 68)
+-- >>> withWriteBuffer 4 $ \wbuf -> write32 wbuf (65 * 256^(3 :: Int) + 66 * 256^(2 :: Int) + 67 * 256 + 68)
 -- "ABCD"
 write32 :: WriteBuffer -> Word32 -> IO ()
 write32 WriteBuffer{..} w = do
@@ -585,6 +586,7 @@
     -- | Returning the length of the remaining
     remainingSize :: a -> IO Int
     -- | Executing an action on the current offset pointer.
+    position :: a -> IO Int
     withCurrentOffSet :: a -> (Buffer -> IO b) -> IO b
     -- | Memorizing the current offset pointer.
     save :: a -> IO ()
@@ -624,6 +626,9 @@
     remainingSize WriteBuffer{..} = do
         ptr <- readIORef offset
         return $ limit `minusPtr` ptr
+    position WriteBuffer{..} = do
+        ptr <- readIORef offset
+        return $ ptr `minusPtr` start
     {-# INLINE withCurrentOffSet #-}
     withCurrentOffSet WriteBuffer{..} action = readIORef offset >>= action
     {-# INLINE save #-}
@@ -647,6 +652,8 @@
     ff (ReadBuffer w) = ff w
     {-# INLINE remainingSize #-}
     remainingSize (ReadBuffer w) = remainingSize w
+    {-# INLINE position #-}
+    position (ReadBuffer w) = position w
     {-# INLINE withCurrentOffSet #-}
     withCurrentOffSet (ReadBuffer w) = withCurrentOffSet w
     {-# INLINE save #-}
diff --git a/network-byte-order.cabal b/network-byte-order.cabal
--- a/network-byte-order.cabal
+++ b/network-byte-order.cabal
@@ -1,42 +1,24 @@
--- Initial network-byte-order.cabal generated by cabal init.  For further
--- documentation, see http://haskell.org/cabal/users-guide/
+cabal-version: >=1.10
+name:          network-byte-order
+version:       0.1.7
+license:       BSD3
+license-file:  LICENSE
+maintainer:    kazu@iij.ad.jp
+author:        Kazu Yamamoto
+synopsis:      Network byte order utilities
+description:   Peek and poke functions for network byte order.
+category:      Network
+build-type:    Simple
 
-name:                network-byte-order
-version:             0.1.6
-synopsis:            Network byte order utilities
-description:         Peek and poke functions for network byte order.
-license:             BSD3
-license-file:        LICENSE
-author:              Kazu Yamamoto
-maintainer:          kazu@iij.ad.jp
--- copyright:
-category:            Network
-build-type:          Simple
--- extra-source-files:  ChangeLog.md
-cabal-version:       >= 1.10
+source-repository head
+    type:     git
+    location: git://github.com/kazu-yamamoto/network-byte-order.git
 
 library
-  ghc-options:         -Wall
-  exposed-modules:     Network.ByteOrder
-  -- other-modules:
-  -- other-extensions:
-  build-depends:       base >= 4.8 && < 5
-                     , bytestring
-  -- hs-source-dirs:
-  default-language:    Haskell2010
-  if impl(ghc >= 8)
-      default-extensions:  Strict StrictData
-
-test-suite doctest
-  type:                 exitcode-stdio-1.0
-  default-language:     Haskell2010
-  hs-source-dirs:       test
-  ghc-options:          -Wall
-  main-is:              doctests.hs
-  build-depends:        base
-                      , bytestring
-                      , doctest
-
-source-repository head
-  type:     git
-  location: git://github.com/kazu-yamamoto/network-byte-order.git
+    exposed-modules:    Network.ByteOrder
+    default-language:   Haskell2010
+    default-extensions: Strict StrictData
+    ghc-options:        -Wall
+    build-depends:
+        base >=4.9 && <5,
+        bytestring
diff --git a/test/doctests.hs b/test/doctests.hs
deleted file mode 100644
--- a/test/doctests.hs
+++ /dev/null
@@ -1,10 +0,0 @@
-module Main where
-
-import Test.DocTest
-
-main :: IO ()
-main = doctest [
-    "-XOverloadedStrings"
-  , "-XCPP"
-  , "Network/ByteOrder.hs"
-  ]