diff --git a/System/Log/FastLogger/Date.hs b/System/Log/FastLogger/Date.hs
--- a/System/Log/FastLogger/Date.hs
+++ b/System/Log/FastLogger/Date.hs
@@ -31,6 +31,6 @@
 zonedDateCacheConf :: DateCacheConf EpochTime
 zonedDateCacheConf = DateCacheConf {
     getTime = epochTime
-  , formatDate = return . formatUnixTime "%d/%b/%Y:%T %z" . fromEpochTime
+  , formatDate = formatUnixTime "%d/%b/%Y:%T %z" . fromEpochTime
   }
 #endif
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:                0.3.1
+Version:                0.3.2
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3