diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,11 @@
 Version change log.
 
+=0.16.1=
+Removed unicode-escaping of illegal identifier characters in the
+pretty-printer. Adjusted the isValid predicate to check for illegal
+characters identifiers. Adjusted the Arbitrary instance to only produce
+valid identifier names.
+
 =0.16=
 Rewritten the Arbitrary instances using 'testing-feat'. Adjusted the
 pretty-printer to escape invalid characters in identifier names
diff --git a/language-ecmascript.cabal b/language-ecmascript.cabal
--- a/language-ecmascript.cabal
+++ b/language-ecmascript.cabal
@@ -1,5 +1,5 @@
 Name:           language-ecmascript
-Version:        0.16
+Version:        0.16.1
 Cabal-Version:	>= 1.10
 Copyright:      (c) 2007-2012 Brown University, (c) 2008-2010 Claudiu Saftoiu,
                 (c) 2012-2014 Stevens Institute of Technology
@@ -29,7 +29,7 @@
 Source-repository this
    type: git
    location: git://github.com/jswebtools/language-ecmascript.git
-   tag: 0.16
+   tag: 0.16.1
 
 Library
   Hs-Source-Dirs:
diff --git a/src/Language/ECMAScript3/PrettyPrint.hs b/src/Language/ECMAScript3/PrettyPrint.hs
--- a/src/Language/ECMAScript3/PrettyPrint.hs
+++ b/src/Language/ECMAScript3/PrettyPrint.hs
@@ -249,43 +249,12 @@
   VarDecl _ id (Just e) -> prettyPrint id <+> equals
                            <+> ppAssignmentExpression hasIn e
 
--- | Pretty prints a string assuming it's used as an
--- identifier. Escapes characters that are disallowed by the grammar
--- with unicode escape sequences, so that the resulting program can be
--- parsed later. Note that it does not (and could not) do anything
--- about identifier names that are reserved words as well as empty
--- identifier names.
+-- | Pretty prints a string assuming it's used as an identifier. Note
+-- that per Spec 7.6 unicode escape sequences representing illegal
+-- identifier characters are not allowed as well, so we do not
+-- unicode-escape illegal characters in identifiers anymore.
 printIdentifierName :: String -> Doc
-printIdentifierName = text . adapt 
-  where adapt [] = []
-        adapt (c:cs) = (adaptStart c) ++ (concatMap adaptRest cs)
-        adaptStart c = if validIdStart c then [c]
-                       else unicodeEscape c
-        adaptRest c = if validIdPart c then [c]
-                      else unicodeEscape c
-        validIdStart c = unicodeLetter c
-                      || c == '$'
-                      || c == '_'
-        validIdPart c = validIdStart c
-                     || validIdPartUnicode c
-        unicodeLetter c = case generalCategory c of
-          UppercaseLetter -> True
-          LowercaseLetter -> True
-          TitlecaseLetter -> True
-          ModifierLetter  -> True
-          OtherLetter     -> True
-          LetterNumber    -> True
-          _               -> False
-        validIdPartUnicode c = case generalCategory c of
-          NonSpacingMark       -> True
-          SpacingCombiningMark -> True
-          DecimalNumber        -> True
-          ConnectorPunctuation -> True
-          _                    -> False
-        -- escapes a given character converting it into a 16-bit
-        -- unicode escape sequence
-        unicodeEscape :: Char -> String
-        unicodeEscape c = "\\u" ++ showHex (ord c) ""
+printIdentifierName = text
 
 -- Based on:
 --   http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Literals
diff --git a/src/Language/ECMAScript3/Syntax.hs b/src/Language/ECMAScript3/Syntax.hs
--- a/src/Language/ECMAScript3/Syntax.hs
+++ b/src/Language/ECMAScript3/Syntax.hs
@@ -27,6 +27,9 @@
                                    ,isValid
                                    ,isValidIdentifier
                                    ,isValidIdentifierName
+                                   ,isReservedWord
+                                   ,isValidIdStart
+                                   ,isValidIdPart
                                    ,EnclosingStatement(..)
                                    ,pushLabel
                                    ,pushEnclosing
@@ -358,8 +361,15 @@
 isValidIdentifier :: Id a -> Bool
 isValidIdentifier (Id _ name) = isValidIdentifierName name
 
+-- | Checks if the 'String' represents a valid identifier name
 isValidIdentifierName :: String -> Bool
-isValidIdentifierName name = (not $ null name) && name `notElem` reservedWords
+isValidIdentifierName name = case name of
+  "" -> False
+  (c:cs) -> isValidIdStart c && and (map isValidIdPart cs) && (not $ isReservedWord name)
+
+-- | Checks if a string is in the list of reserved ECMAScript words
+isReservedWord :: String -> Bool
+isReservedWord = (`elem` reservedWords)
   where reservedWords = keyword ++ futureReservedWord ++ nullKw ++ boolLit
         keyword = ["break", "case", "catch", "continue", "default", "delete"
                   ,"do", "else", "finally", "for", "function", "if", "in"
@@ -373,6 +383,29 @@
                              ,"synchronized", "throws", "transient", "volatile"]
         nullKw = ["null"]
         boolLit = ["true", "false"]
+
+-- | Checks if a character is valid at the start of an identifier
+isValidIdStart :: Char -> Bool
+isValidIdStart c = unicodeLetter c || c == '$' || c == '_'
+  where unicodeLetter c = case generalCategory c of
+          UppercaseLetter -> True
+          LowercaseLetter -> True
+          TitlecaseLetter -> True
+          ModifierLetter  -> True
+          OtherLetter     -> True
+          LetterNumber    -> True
+          _               -> False
+
+-- | Checks if a character is valid in an identifier part
+isValidIdPart :: Char -> Bool
+isValidIdPart c = isValidIdStart c || isValidIdPartUnicode c
+  where isValidIdPartUnicode c = case generalCategory c of
+          NonSpacingMark       -> True
+          SpacingCombiningMark -> True
+          DecimalNumber        -> True
+          ConnectorPunctuation -> True
+          _                    -> False
+        
           
 data EnclosingStatement = EnclosingIter [Label]
                           -- ^ The enclosing statement is an iteration statement
diff --git a/src/Language/ECMAScript3/Syntax/Arbitrary.hs b/src/Language/ECMAScript3/Syntax/Arbitrary.hs
--- a/src/Language/ECMAScript3/Syntax/Arbitrary.hs
+++ b/src/Language/ECMAScript3/Syntax/Arbitrary.hs
@@ -267,10 +267,17 @@
 identifierFixup (Id a n) = Id a $ identifierNameFixup n
 
 -- | Renames empty identifiers, as well as identifiers that are
--- keywords or future reserved words by prepending a '_' to them
+-- keywords or future reserved words by prepending a '_' to them. Also
+-- substitutes illegal characters with a "_" as well.
 identifierNameFixup :: String -> String
-identifierNameFixup name = if isValidIdentifierName name then name
-                           else '_':name
+identifierNameFixup s =
+  let fixStart c = if isValidIdStart c then c else '_'
+      fixPart c  = if isValidIdPart c  then c else '_'
+  in case s of
+    "" -> "_"
+    (start:part) -> let fixed_id = (fixStart start):(map fixPart part)
+                    in if isReservedWord fixed_id then '_':fixed_id
+                       else fixed_id
 
 -- | Fixes an incorrect nesting of break/continue, making the program
 -- abide by the ECMAScript spec (page 92): any continue without a