diff --git a/bench/Bench.hs b/bench/Bench.hs
index bbb183f038ddb2a9bd0964d7b5bf34c584168479..587ac57a91e939faea4fe1301f43a841888684cf 100644
--- a/bench/Bench.hs
+++ b/bench/Bench.hs
@@ -2,6 +2,7 @@
 -- License, v. 2.0. If a copy of the MPL was not distributed with this
 -- file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+{-# LANGUAGE BangPatterns      #-}
 {-# LANGUAGE OverloadedStrings #-}
 
 module Main (main) where
@@ -9,44 +10,71 @@ module Main (main) where
 import Criterion
 import Criterion.Main
 import Data.Int
+import Data.Monoid
 import System.Logger.Message
 
-import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString.Builder as B
+import qualified Data.ByteString.Lazy    as L
 
 main :: IO ()
 main = defaultMain
     [ bgroup "direct"
-        [ bench "msg/8"  (whnf (f False) 8)
-        , bench "msg/16" (whnf (f False) 16)
-        , bench "msg/32" (whnf (f False) 32)
+        [ bench "msg/8"  (whnf (f renderDefault) 8)
+        , bench "msg/16" (whnf (f renderDefault) 16)
+        , bench "msg/32" (whnf (f renderDefault) 32)
         ]
     , bgroup "netstr"
-        [ bench "msg/8"  (whnf (f True) 8)
-        , bench "msg/16" (whnf (f True) 16)
-        , bench "msg/32" (whnf (f True) 32)
+        [ bench "msg/8"  (whnf (f renderNetstr) 8)
+        , bench "msg/16" (whnf (f renderNetstr) 16)
+        , bench "msg/32" (whnf (f renderNetstr) 32)
+        ]
+    , bgroup "custom"
+        [ bench "msg/8"  (whnf (f renderCustom) 8)
+        , bench "msg/16" (whnf (f renderCustom) 16)
+        , bench "msg/32" (whnf (f renderCustom) 32)
         ]
     , bgroup "direct"
-        [ bench "field/8"  (whnf (g False) 8)
-        , bench "field/16" (whnf (g False) 16)
-        , bench "field/32" (whnf (g False) 32)
+        [ bench "field/8"  (whnf (g renderDefault) 8)
+        , bench "field/16" (whnf (g renderDefault) 16)
+        , bench "field/32" (whnf (g renderDefault) 32)
         ]
     , bgroup "netstr"
-        [ bench "field/8"  (whnf (g True) 8)
-        , bench "field/16" (whnf (g True) 16)
-        , bench "field/32" (whnf (g True) 32)
+        [ bench "field/8"  (whnf (g renderNetstr) 8)
+        , bench "field/16" (whnf (g renderNetstr) 16)
+        , bench "field/32" (whnf (g renderNetstr) 32)
+        ]
+    , bgroup "custom"
+        [ bench "field/8"  (whnf (g renderCustom) 8)
+        , bench "field/16" (whnf (g renderCustom) 16)
+        , bench "field/32" (whnf (g renderCustom) 32)
         ]
     ]
 
-f :: Bool -> Int -> Int64
-f b n = L.length
-      . render ", " b
+f :: Renderer -> Int -> Int64
+f r n = L.length
+      . render ", " r
       . foldr1 (.)
       . replicate n
       $ msg (val "hello world" +++ (10000 :: Int) +++ (-42 :: Int64))
 
-g :: Bool -> Int -> Int64
-g b n = L.length
-      . render ", " b
+g :: Renderer -> Int -> Int64
+g r n = L.length
+      . render ", " r
       . foldr1 (.)
       . replicate n
       $ "key" .= (val "hello world" +++ (10000 :: Int) +++ (-42 :: Int64))
+
+
+renderCustom :: Renderer
+renderCustom s = encAll mempty
+  where
+    encAll !acc    []  = acc
+    encAll !acc (b:[]) = acc <> encOne b
+    encAll !acc (b:bb) = encAll (acc <> encOne b <> sep) bb
+
+    encOne (Bytes b)   = builderBytes b
+    encOne (Field k v) = builderBytes k <> eq <> quo <> builderBytes v <> quo
+
+    eq  = B.char8 '='
+    quo = B.char8 '"'
+    sep = B.byteString s
diff --git a/src/System/Logger.hs b/src/System/Logger.hs
index d14b9ce5f2af4965a9f3156e93f289706dd3c23e..a989749a3327d9fafca38ce201a668e39435af56 100644
--- a/src/System/Logger.hs
+++ b/src/System/Logger.hs
@@ -21,7 +21,6 @@ module System.Logger
     , setFormat
     , delimiter
     , setDelimiter
-    , netstrings
     , setNetStrings
     , bufSize
     , setBufSize
@@ -109,7 +108,7 @@ new s = liftIO $ do
     !m <- fromMaybe "[]" <$> lookupEnv "LOG_LEVEL_MAP"
     let !k  = logLevelMap s `mergeWith` m
     let !s' = setLogLevel (fromMaybe (logLevel s) l)
-            . setNetStrings (fromMaybe (netstrings s) e)
+            . setNetStrings (fromMaybe False e)
             . setLogLevelMap k
             $ s
     g <- fn (output s) (fromMaybe (bufSize s) n)
@@ -182,10 +181,10 @@ level = logLevel . settings
 putMsg :: MonadIO m => Logger -> Level -> (Msg -> Msg) -> m ()
 putMsg g l f = liftIO $ do
     d <- getDate g
-    let n = netstrings $ settings g
-    let x = delimiter  $ settings g
-    let s = nameMsg    $ settings g
-    let m = render x n (d . lmsg l . s . f)
+    let r = renderer  $ settings g
+    let x = delimiter $ settings g
+    let s = nameMsg   $ settings g
+    let m = render x r (d . lmsg l . s . f)
     FL.pushLogStr (logger g) (FL.toLogStr m)
 
 lmsg :: Level -> (Msg -> Msg)
diff --git a/src/System/Logger/Class.hs b/src/System/Logger/Class.hs
index ddc00df566c4c3b4c1e1af19dd5dffd54205e3b4..2e02d4ec1aad9680d9c1166a5f8558f2ef77c449 100644
--- a/src/System/Logger/Class.hs
+++ b/src/System/Logger/Class.hs
@@ -16,7 +16,6 @@ module System.Logger.Class
     , L.setFormat
     , L.delimiter
     , L.setDelimiter
-    , L.netstrings
     , L.setNetStrings
     , L.bufSize
     , L.setBufSize
diff --git a/src/System/Logger/Message.hs b/src/System/Logger/Message.hs
index 2cfbbee5f435b5742a8922afedeb1784ce3b1914..ba925662a5469aea143756bc0b68ce16a8046b82 100644
--- a/src/System/Logger/Message.hs
+++ b/src/System/Logger/Message.hs
@@ -19,6 +19,8 @@ module System.Logger.Message
     ( ToBytes (..)
     , Msg
     , Builder
+    , Element (..)
+    , Renderer
     , msg
     , field
     , (.=)
@@ -26,7 +28,11 @@ module System.Logger.Message
     , (~~)
     , val
     , eval
+    , builderSiz
+    , builderBytes
     , render
+    , renderDefault
+    , renderNetstr
     ) where
 
 import Data.ByteString (ByteString)
@@ -59,6 +65,12 @@ instance IsString Builder where
 eval :: Builder -> L.ByteString
 eval (Builder n b) = B.toLazyByteStringWith (B.safeStrategy n 256) L.empty b
 
+builderSiz :: Builder -> Int
+builderSiz (Builder n _) = n
+
+builderBytes :: Builder -> B.Builder
+builderBytes (Builder _ b) = b
+
 -- | Convert some value to a 'Builder'.
 class ToBytes a where
     bytes :: a -> Builder
@@ -98,6 +110,8 @@ len10 !n = if n > 0 then go n 0 else 1 + go (-n) 0
 -- | Type representing log messages.
 newtype Msg = Msg { elements :: [Element] }
 
+type Renderer = ByteString -> [Element] -> B.Builder
+
 data Element
     = Bytes Builder
     | Field Builder Builder
@@ -133,22 +147,11 @@ val = bytes
 
 -- | Intersperse parts of the log message with the given delimiter and
 -- render the whole builder into a 'L.ByteString'.
---
--- If the second parameter is set to @True@, netstrings encoding is used for
--- the message elements. Cf. <http://cr.yp.to/proto/netstrings.txt> for
--- details.
-render :: ByteString -> Bool -> (Msg -> Msg) -> L.ByteString
-render _ True m = finish . encAll mempty . elements . m $ empty
-  where
-    encAll !acc []     = acc
-    encAll !acc (b:bb) = encAll (acc <> encOne b) bb
+render :: ByteString -> Renderer -> (Msg -> Msg) -> L.ByteString
+render s f m = finish . f s . elements . m $ empty
 
-    encOne (Bytes   e) = netstr e
-    encOne (Field k v) = netstr k <> eq <> netstr v
-
-    eq = B.byteString "1:=,"
-
-render s False m = finish . encAll mempty . elements . m $ empty
+renderDefault :: Renderer
+renderDefault s = encAll mempty
   where
     encAll !acc    []  = acc
     encAll !acc (b:[]) = acc <> encOne b
@@ -160,6 +163,17 @@ render s False m = finish . encAll mempty . elements . m $ empty
     eq  = B.char8 '='
     sep = B.byteString s
 
+renderNetstr :: Renderer
+renderNetstr _ = encAll mempty
+  where
+    encAll !acc []     = acc
+    encAll !acc (b:bb) = encAll (acc <> encOne b) bb
+
+    encOne (Bytes   e) = netstr e
+    encOne (Field k v) = netstr k <> eq <> netstr v
+
+    eq = B.byteString "1:=,"
+
 finish :: B.Builder -> L.ByteString
 finish = B.toLazyByteStringWith (B.untrimmedStrategy 256 256) "\n"
 
diff --git a/src/System/Logger/Settings.hs b/src/System/Logger/Settings.hs
index 9b852f3d8e12d34076e8719b8a6db9d79747ef55..f83c61a965533f77ec8f8140f8d998429f237f36 100644
--- a/src/System/Logger/Settings.hs
+++ b/src/System/Logger/Settings.hs
@@ -19,7 +19,6 @@ module System.Logger.Settings
     , setBufSize
     , delimiter
     , setDelimiter
-    , netstrings
     , setNetStrings
     , logLevel
     , logLevelMap
@@ -30,6 +29,8 @@ module System.Logger.Settings
     , name
     , setName
     , nameMsg
+    , renderer
+    , setRenderer
     , iso8601UTC
     ) where
 
@@ -42,16 +43,18 @@ import Data.UnixTime
 import System.Log.FastLogger (defaultBufSize)
 import System.Logger.Message
 
+import qualified Data.ByteString.Builder as B
+
 data Settings = Settings
     { _logLevel   :: !Level              -- ^ messages below this log level will be suppressed
     , _levelMap   :: !(Map Text Level)   -- ^ log level per named logger
     , _output     :: !Output             -- ^ log sink
     , _format     :: !(Maybe DateFormat) -- ^ the timestamp format (use 'Nothing' to disable timestamps)
     , _delimiter  :: !ByteString         -- ^ text to intersperse between fields of a log line
-    , _netstrings :: !Bool               -- ^ use <http://cr.yp.to/proto/netstrings.txt netstrings> encoding (fixes delimiter to \",\")
     , _bufSize    :: !Int                -- ^ how many bytes to buffer before commiting to sink
     , _name       :: !(Maybe Text)       -- ^ logger name
     , _nameMsg    :: !(Msg -> Msg)
+    , _renderer   :: !(ByteString -> [Element] -> B.Builder)
     }
 
 output :: Settings -> Output
@@ -82,11 +85,9 @@ setDelimiter x s = s { _delimiter = x }
 
 -- | Whether to use <http://cr.yp.to/proto/netstrings.txt netstring>
 -- encoding for log lines.
-netstrings :: Settings -> Bool
-netstrings = _netstrings
-
 setNetStrings :: Bool -> Settings -> Settings
-setNetStrings x s = s { _netstrings = x }
+setNetStrings True  = setRenderer renderNetstr
+setNetStrings False = setRenderer renderDefault
 
 logLevel :: Settings -> Level
 logLevel = _logLevel
@@ -120,6 +121,13 @@ setName (Just xs) s = s { _name = Just xs, _nameMsg = "logger" .= xs }
 nameMsg :: Settings -> (Msg -> Msg)
 nameMsg = _nameMsg
 
+-- | Output format
+renderer :: Settings -> (ByteString -> [Element] -> B.Builder)
+renderer = _renderer
+
+setRenderer :: (ByteString -> [Element] -> B.Builder) -> Settings -> Settings
+setRenderer f s = s { _renderer = f }
+
 data Level
     = Trace
     | Debug
@@ -169,7 +177,7 @@ defSettings = Settings
     StdOut
     (Just iso8601UTC)
     ", "
-    False
     defaultBufSize
     Nothing
     id
+    renderDefault