diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 0.3.10.1
+
+Remove unnecessary extra newline in log messages.
+
 ## 0.3.10
 
 Introduce the `MonadLoggerIO` typeclass.
diff --git a/Control/Monad/Logger.hs b/Control/Monad/Logger.hs
--- a/Control/Monad/Logger.hs
+++ b/Control/Monad/Logger.hs
@@ -453,7 +453,7 @@
               -> LogStr
               -> IO ()
 defaultOutput h loc src level msg =
-    S8.hPutStrLn h ls
+    S8.hPutStr h ls
   where
     ls = defaultLogStrBS loc src level msg
 defaultLogStrBS :: Loc
diff --git a/monad-logger.cabal b/monad-logger.cabal
--- a/monad-logger.cabal
+++ b/monad-logger.cabal
@@ -1,5 +1,5 @@
 name:                monad-logger
-version:             0.3.10
+version:             0.3.10.1
 synopsis:            A class of monads which can log messages.
 description:         This package uses template-haskell for determining source code locations of messages.
 homepage:            https://github.com/kazu-yamamoto/logger