diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.4.3
+
+* Opening files in the append mode on Windows.
+
 ## 2.4.2
 
 * Fixing a buf of long log messages [#80](https://github.com/kazu-yamamoto/logger/pull/80)
diff --git a/System/Log/FastLogger/FileIO.hs b/System/Log/FastLogger/FileIO.hs
--- a/System/Log/FastLogger/FileIO.hs
+++ b/System/Log/FastLogger/FileIO.hs
@@ -6,19 +6,23 @@
 import Data.Word (Word8)
 
 #ifdef mingw32_HOST_OS
-import System.Win32.Types (HANDLE)
+import System.Win32.Types (HANDLE, UINT)
 import System.Win32.File
 import Graphics.Win32.Misc (getStdHandle, sTD_OUTPUT_HANDLE, sTD_ERROR_HANDLE)
 import Data.Bits ((.|.))
 
 type FD = HANDLE
 
+-- This flag is not defined in System.Win32.File
+fILE_APPEND_DATA :: UINT
+fILE_APPEND_DATA = 0x0004
+
 closeFD :: FD -> IO ()
 closeFD = closeHandle
 
 openFileFD :: FilePath -> IO FD
 openFileFD f = createFile f
-                         (gENERIC_READ .|. gENERIC_WRITE)
+                         fILE_APPEND_DATA
                          (fILE_SHARE_READ .|. fILE_SHARE_DELETE)
                          Nothing
                          oPEN_ALWAYS
diff --git a/fast-logger.cabal b/fast-logger.cabal
--- a/fast-logger.cabal
+++ b/fast-logger.cabal
@@ -1,5 +1,5 @@
 Name:                   fast-logger
-Version:                2.4.2
+Version:                2.4.3
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3