diff --git a/AttoJson.cabal b/AttoJson.cabal
--- a/AttoJson.cabal
+++ b/AttoJson.cabal
@@ -1,5 +1,5 @@
 Name:                AttoJson
-Version:             0.5.8
+Version:             0.5.9
 Synopsis:            Simple lightweight JSON parser, generator & manipulator based on ByteString
 
 Description: Simple Lightweight JSON parser & generator based on ByteString.
@@ -8,7 +8,7 @@
 License:             BSD3
 License-file:        LICENSE
 Author:              Hiromi ISHII
-Maintainer:          mr_konn _at_ jcom.home.ne.jp
+Maintainer:          konn.jinro _at_ gmail.com
 Category:            Text
 Build-type:          Simple
 Cabal-version:       >=1.6
diff --git a/Text/JSON/AttoJSON.hs b/Text/JSON/AttoJSON.hs
--- a/Text/JSON/AttoJSON.hs
+++ b/Text/JSON/AttoJSON.hs
@@ -9,7 +9,7 @@
     -- * Manipulating Objects
     lookup, getField, findWithDefault,
     lookupDeep, getFields, findDeepWithDefault,
-    updateField
+    updateField, updateFields
   ) where
 
 import Control.Applicative hiding (many)
@@ -88,6 +88,9 @@
 updateField key v (JSObject jso) = JSObject $ insert key (toJSON v) jso
 updateField _ _ j                = j
 
+updateFields :: [(ByteString, JSValue)] -> JSValue -> JSValue
+updateFields = flip (foldr (\(k,v) -> updateField k v))
+
 -- |Type Class for the value that can be converted from/into 'JSValue'.
 class JSON a where
     -- |Decode from JSValue
@@ -192,26 +195,27 @@
 -- |Print 'JSValue' as JSON source (not pretty).
 --
 --  The output string will be in UTF8 (provided the JSValue was constructed with UTF8 strings).
+--  Only characters that have to be escaped (control characters, @\\@, and @\"@) will be escaped.
 showJSON :: JSValue -> ByteString
-showJSON (JSObject dic) = "{" `append` intercalate "," mems `append` "}"
-  where
-    mems = elems $ mapWithKey (\k v -> showJSString False k `append` ":" `append` showJSON v) dic
-showJSON (JSString jss)     = showJSString False jss
-showJSON (JSNumber jsn) | denominator jsn == 1 = fromLazy $ show $ numerator jsn
-                        | otherwise            = fromLazy $ show (fromRational jsn :: Double)
-showJSON (JSArray jss)      = "[" `append` intercalate ", " (P.map showJSON jss) `append` "]"
-showJSON (JSNull)           = "null"
-showJSON (JSBool True)      = "true"
-showJSON (JSBool False)     = "false"
+showJSON = showJSONEsc False
 
--- |Same as 'showJSON', but escape Unicode Charactors.
+-- |Same as 'showJSON', but escape non-ASCII characters as well.
 showJSON' :: JSValue -> ByteString
-showJSON' (JSObject dic) = "{" `append` intercalate "," mems `append` "}"
+showJSON' = showJSONEsc True
+
+showJSONEsc :: Bool -> JSValue -> ByteString
+showJSONEsc esc (JSObject dic) = "{" `append` intercalate "," mems `append` "}"
   where
-    mems = elems $ mapWithKey (\k v -> showJSString True k `append` ":" `append` showJSON v) dic
-showJSON' (JSString jss) = showJSString True jss
-showJSON' jsv            = showJSON jsv
+    mems = elems $ mapWithKey (\k v -> showJSString esc k `append` ":" `append` showJSONEsc esc v) dic
+showJSONEsc esc (JSString jss)     = showJSString esc jss
+showJSONEsc esc (JSNumber jsn) | denominator jsn == 1 = fromLazy $ show $ numerator jsn
+                               | otherwise            = fromLazy $ show (fromRational jsn :: Double)
+showJSONEsc esc (JSArray jss)      = "[" `append` intercalate ", " (P.map (showJSONEsc esc) jss) `append` "]"
+showJSONEsc esc (JSNull)           = "null"
+showJSONEsc esc (JSBool True)      = "true"
+showJSONEsc esc (JSBool False)     = "false"
 
+
 showJSString :: Bool -> ByteString -> ByteString
 showJSString escapeU js = "\"" `append` escape js `append` "\""
   where
@@ -226,8 +230,9 @@
     escapeCh '\n' = "\\n"
     escapeCh '\r' = "\\r"
     escapeCh '\t' = "\\t"
-    escapeCh ch | mustEscape ch || (escapeU && ch > '\xff') = escapeHex $ fromEnum ch
-                | otherwise           = fromString [ch]
+    escapeCh ch | mustEscape ch || (escapeU && ch > '\x7f')
+                            = escapeHex $ fromEnum ch
+                | otherwise = fromString [ch]
 
 jsNull = lexeme (JSNull <$ symbol "null")
 bool   = lexeme $
@@ -316,15 +321,24 @@
   where (a,b) = toSurrogatePair n
 
 fromSurrogatePair :: (Int,Int) -> Int
-fromSurrogatePair (uc,lc) = 0x10000 .|. a .|. b where
+fromSurrogatePair (uc,lc) = (a .|. b) + 0x10000 where
   a = (uc .&. 0x3ff) `shiftL` 10
   b = lc .&. 0x3ff
 
 toSurrogatePair :: Int -> (Int,Int)
 toSurrogatePair n = (a + 0xd800, b + 0xdc00) where
-  a = (n `shiftR` 10) .&. 0x3ff
-  b = n .&. 0x3ff
+  n' = n - 0x10000
+  a = (n' `shiftR` 10) .&. 0x3ff
+  b = n' .&. 0x3ff
 
+testSurrogatePairFuncs :: Bool
+testSurrogatePairFuncs = fromPassed && toPassed where
+    pairs  = [(uc, lc) | uc <- [0xd800..0xdbff], lc <- [0xdc00..0xdfff]]
+    values = [0x10000..0x10FFFF]
+    fromPassed = and $ zipWith (\p v -> fromSurrogatePair p == v) pairs values
+    toPassed   = and $ zipWith (\p v -> p == toSurrogatePair v)   pairs values
+
 toHexChar :: Int -> Char
 toHexChar d | 0 <= d && d <= 9 = toEnum $ 48 + d
             | 10 <= d          = toEnum $ 87 + d 
+