diff --git a/Network/Sendfile/BSD.hsc b/Network/Sendfile/BSD.hsc
--- a/Network/Sendfile/BSD.hsc
+++ b/Network/Sendfile/BSD.hsc
@@ -74,7 +74,9 @@
         if errno `elem` [eAGAIN, eINTR] then do
             sent <- peek sentp
             hook
-            threadWaitWrite dst
+            -- Parallel IO manager use edge-trigger mode.
+            -- So, calling threadWaitWrite only when errnor is eAGAIN.
+            when (errno == eAGAIN) $ threadWaitWrite dst
             let newoff = off + sent
                 newlen = if len == entire then entire else len - sent
             sendloop dst src newoff newlen sentp hook
@@ -163,7 +165,9 @@
                   else
                     return $ Just (newoff, len - sent)
               else do
-                threadWaitWrite dst
+                -- Parallel IO manager use edge-trigger mode.
+                -- So, calling threadWaitWrite only when errnor is eAGAIN.
+                when (errno == eAGAIN) $ threadWaitWrite dst
                 let newlen = if len == entire then entire else len - sent
                     newhdr = remainingChunks (fromIntegral sent) hdr
                     newhlen = hlen - sent
diff --git a/Network/Sendfile/Linux.hsc b/Network/Sendfile/Linux.hsc
--- a/Network/Sendfile/Linux.hsc
+++ b/Network/Sendfile/Linux.hsc
@@ -102,7 +102,9 @@
     loop 0    = return ()
     loop left = do
         hook
-        threadWaitWrite dst
+        -- Parallel IO manager use edge-trigger mode.
+        -- So, calling threadWaitWrite only when errnor is eAGAIN.
+        when (errno == eAGAIN) $ threadWaitWrite dst
         sendloop dst src offp left hook
 
 -- Dst Src in order. take care
diff --git a/simple-sendfile.cabal b/simple-sendfile.cabal
--- a/simple-sendfile.cabal
+++ b/simple-sendfile.cabal
@@ -1,5 +1,5 @@
 Name:                   simple-sendfile
-Version:                0.2.8
+Version:                0.2.9
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3
@@ -11,7 +11,6 @@
 Category:               Network
 Cabal-Version:          >= 1.10
 Build-Type:             Simple
-Extra-Source-Files:     test/setup.sh
 
 Library
   Default-Language:     Haskell2010
@@ -47,9 +46,8 @@
   Type:                 exitcode-stdio-1.0
   Default-Language:     Haskell2010
   Hs-Source-Dirs:       test
-  Main-Is:              Spec.hs
+  Main-Is:              SendfileSpec.hs
   GHC-Options:          -Wall
-  Other-Modules:        SendfileSpec
   Build-Depends:        base
                       , HUnit
                       , bytestring
diff --git a/test/SendfileSpec.hs b/test/SendfileSpec.hs
--- a/test/SendfileSpec.hs
+++ b/test/SendfileSpec.hs
@@ -1,11 +1,12 @@
 {-# LANGUAGE OverloadedStrings #-}
 
-module SendfileSpec where
+module Main where
 
 import Control.Concurrent
 import Control.Exception
 import Control.Monad
-import Data.ByteString.Char8 as BS
+import Data.ByteString (ByteString)
+import qualified Data.ByteString.Char8 as BS
 import Data.Conduit
 import Data.Conduit.Binary as CB
 import Data.Conduit.List as CL
@@ -23,10 +24,16 @@
 
 ----------------------------------------------------------------
 
+main :: IO ()
+main = do
+    setup0
+    hspec spec
+
 spec :: Spec
 spec = do
     describe "sendfile" $ do
         it "sends an entire file" $ do
+            setup0
             sendFile EntireFile `shouldReturn` ExitSuccess
         it "sends a part of file" $ do
             sendFile (PartOfFile 2000 1000000) `shouldReturn` ExitSuccess
@@ -215,3 +222,30 @@
                   => FilePath
                   -> Sink ByteString m ()
 sinkAppendFile fp = sinkIOHandle (openBinaryFile fp AppendMode)
+
+----------------------------------------------------------------
+
+srcFile :: String
+srcFile = "/usr/share/dict/words"
+
+dstFile :: String
+dstFile = "test/inputFile"
+
+setup0 :: IO ()
+setup0 = do
+    dst <- doesFileExist dstFile
+    unless dst $ do
+        src <- doesFileExist srcFile
+        if src then do
+            size <- getFileSize srcFile
+            if size >= 1000000 then
+                copyFile srcFile dstFile
+              else
+                failure
+          else
+            failure
+  where
+    getFileSize file = bracket (openFile file ReadMode) hClose hFileSize
+    failure = do
+        hPutStrLn stderr "You must copy a large file (> 1000000 bytes) to \"test/inputFile\"."
+        exitFailure
diff --git a/test/Spec.hs b/test/Spec.hs
deleted file mode 100644
--- a/test/Spec.hs
+++ /dev/null
@@ -1,1 +0,0 @@
-{-# OPTIONS_GHC -F -pgmF hspec-discover #-}
diff --git a/test/setup.sh b/test/setup.sh
deleted file mode 100644
--- a/test/setup.sh
+++ /dev/null
@@ -1,3 +0,0 @@
-#! /bin/sh
-
-ln -s /usr/share/dict/words inputFile