diff --git a/Network/ByteOrder.hs b/Network/ByteOrder.hs
--- a/Network/ByteOrder.hs
+++ b/Network/ByteOrder.hs
@@ -69,6 +69,7 @@
   ) where
 
 import Control.Exception (bracket, throwIO, Exception)
+import Control.Monad (when)
 import Data.Bits (shiftR, shiftL, (.&.), (.|.))
 import Data.ByteString.Internal (ByteString(..), create, memcpy, ByteString(..), unsafeCreate)
 import Data.ByteString.Short (ShortByteString)
@@ -378,11 +379,9 @@
 write8 WriteBuffer{..} w = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` 1
-    if ptr' > limit then
-        throwIO BufferOverrun
-      else do
-        poke ptr w
-        writeIORef offset ptr'
+    when (ptr' > limit) $ throwIO BufferOverrun
+    poke ptr w
+    writeIORef offset ptr'
 
 {-# INLINE write16 #-}
 -- | Write two bytes and ff one byte.
@@ -394,11 +393,9 @@
 write16 WriteBuffer{..} w = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` 2
-    if ptr' > limit then
-        throwIO BufferOverrun
-      else do
-        poke16 w ptr 0
-        writeIORef offset ptr'
+    when (ptr' > limit) $ throwIO BufferOverrun
+    poke16 w ptr 0
+    writeIORef offset ptr'
 
 {-# INLINE write24 #-}
 -- | Write three bytes and ff one byte.
@@ -410,11 +407,9 @@
 write24 WriteBuffer{..} w = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` 3
-    if ptr' > limit then
-        throwIO BufferOverrun
-      else do
-        poke24 w ptr 0
-        writeIORef offset ptr'
+    when (ptr' > limit) $ throwIO BufferOverrun
+    poke24 w ptr 0
+    writeIORef offset ptr'
 
 {-# INLINE write32 #-}
 -- | Write four bytes and ff one byte.
@@ -426,11 +421,9 @@
 write32 WriteBuffer{..} w = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` 4
-    if ptr' > limit then
-        throwIO BufferOverrun
-      else do
-        poke32 w ptr 0
-        writeIORef offset ptr'
+    when (ptr' > limit) $ throwIO BufferOverrun
+    poke32 w ptr 0
+    writeIORef offset ptr'
 
 {-# INLINE write64 #-}
 -- | Write four bytes and ff one byte.
@@ -439,11 +432,9 @@
 write64 WriteBuffer{..} w = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` 8
-    if ptr' > limit then
-        throwIO BufferOverrun
-      else do
-        poke64 w ptr 0
-        writeIORef offset ptr'
+    when (ptr' > limit) $ throwIO BufferOverrun
+    poke64 w ptr 0
+    writeIORef offset ptr'
 
 {-# INLINE shiftLastN #-}
 -- | Shifting the N-bytes area just before the current pointer (the 3rd argument).
@@ -462,9 +453,8 @@
 shiftLastN WriteBuffer{..} i len = do
     ptr <- readIORef offset
     let ptr' = ptr `plusPtr` i
-    if ptr' >= limit then
-        throwIO BufferOverrun
-      else if i < 0 then do
+    when (ptr' >= limit) $ throwIO BufferOverrun
+    if i < 0 then do
         let src = ptr `plusPtr` negate len
             dst = src `plusPtr` i
         shiftLeft dst src len
@@ -498,11 +488,9 @@
     let src = ptr `plusPtr` off
     dst <- readIORef offset
     let dst' = dst `plusPtr` len
-    if dst' > limit then
-        throwIO BufferOverrun
-      else do
-        memcpy dst src len
-        writeIORef offset dst'
+    when (dst' > limit) $ throwIO BufferOverrun
+    memcpy dst src len
+    writeIORef offset dst'
 
 -- | Copy the content of 'ShortByteString' and ff its length.
 --   If buffer overrun occurs, 'BufferOverrun' is thrown.
@@ -514,11 +502,9 @@
     dst <- readIORef offset
     let len = Short.length sbs
     let dst' = dst `plusPtr` len
-    if dst' > limit then
-        throwIO BufferOverrun
-      else do
-        Short.copyToPtr sbs 0 dst len
-        writeIORef offset dst'
+    when (dst' > limit) $ throwIO BufferOverrun
+    Short.copyToPtr sbs 0 dst len
+    writeIORef offset dst'
 
 -- | Copy the area from 'start' to the current pointer to 'ByteString'.
 toByteString :: WriteBuffer -> IO ByteString
@@ -580,8 +566,10 @@
     {-# INLINE read8 #-}
     read8 WriteBuffer{..} = do
         ptr <- readIORef offset
+        let ptr' = ptr `plusPtr` 1
+        when (ptr' > limit) $ throwIO BufferOverrun
         w <- peek ptr
-        writeIORef offset $ ptr `plusPtr` 1
+        writeIORef offset ptr'
         return w
     {-# INLINE readInt8 #-}
     readInt8 WriteBuffer{..} = do
@@ -658,6 +646,7 @@
 extractByteString rbuf len
   | len == 0 = return mempty
   | len >  0 = do
+    checkR rbuf len
     bs <- withCurrentOffSet rbuf $ \src ->
         create len $ \dst -> memcpy dst src len
     ff rbuf len
@@ -679,6 +668,7 @@
 extractShortByteString rbuf len
   | len == 0 = return mempty
   | len >  0 = do
+    checkR rbuf len
     sbs <- withCurrentOffSet rbuf $ \src -> Short.createFromPtr src len
     ff rbuf len
     return sbs
@@ -693,6 +683,7 @@
 -- 1
 read16 :: Readable a => a -> IO Word16
 read16 rbuf = do
+    checkR rbuf 2
     w16 <- withCurrentOffSet rbuf (`peek16` 0)
     ff rbuf 2
     return w16
@@ -703,6 +694,7 @@
 -- 258
 read24 :: Readable a => a -> IO Word32
 read24 rbuf = do
+    checkR rbuf 3
     w24 <- withCurrentOffSet rbuf (`peek24` 0)
     ff rbuf 3
     return w24
@@ -713,6 +705,7 @@
 -- 66051
 read32 :: Readable a => a -> IO Word32
 read32 rbuf = do
+    checkR rbuf 4
     w32 <- withCurrentOffSet rbuf (`peek32` 0)
     ff rbuf 4
     return w32
@@ -720,9 +713,15 @@
 -- | Reading four bytes as 'Word64' and ff four bytes.
 read64 :: Readable a => a -> IO Word64
 read64 rbuf = do
+    checkR rbuf 8
     w64 <- withCurrentOffSet rbuf (`peek64` 0)
     ff rbuf 8
     return w64
+
+checkR :: Readable a => a -> Int -> IO ()
+checkR rbuf siz = do
+    left <- remainingSize rbuf
+    when (left < siz) $ throwIO BufferOverrun
 
 -- | Buffer overrun exception.
 data BufferOverrun = BufferOverrun -- ^ The buffer size is not enough
diff --git a/network-byte-order.cabal b/network-byte-order.cabal
--- a/network-byte-order.cabal
+++ b/network-byte-order.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                network-byte-order
-version:             0.1.3.0
+version:             0.1.4.0
 synopsis:            Network byte order utilities
 description:         Peek and poke functions for network byte order.
 license:             BSD3