diff --git a/Network/Wai/Logger.hs b/Network/Wai/Logger.hs
--- a/Network/Wai/Logger.hs
+++ b/Network/Wai/Logger.hs
@@ -90,7 +90,6 @@
 
 stdoutLogger :: IPAddrSource -> DateRef -> ApacheLogger
 stdoutLogger ipsrc dateref req status msiz =
-    getDate dateref >>= hPutLogStr stdout . logmsg
+    getDate dateref >>= hPutLogStr stdout . logmsg >> hFlush stdout
   where
     logmsg date = apacheFormat ipsrc date req status msiz
-
diff --git a/wai-logger.cabal b/wai-logger.cabal
--- a/wai-logger.cabal
+++ b/wai-logger.cabal
@@ -1,5 +1,5 @@
 Name:                   wai-logger
-Version:                0.1.3
+Version:                0.1.4
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3