diff --git a/lib/output.js b/lib/output.js
index a3c6b4ab..62dbf49b 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -134,7 +134,7 @@ function OutputStream(options) {
 
     function make_string(str, quote) {
         var dq = 0, sq = 0;
-        str = str.replace(/[\\\b\f\n\r\v\t\x22\x27\u2028\u2029\0\ufeff]/g,
+        str = str.replace(/[\\\b\f\n\r\v\t\x22\x27\u2028\u2029\0\ufeff\uffff]/g,
           function(s, i){
             switch (s) {
               case '"': ++dq; return '"';
@@ -149,6 +149,7 @@ function OutputStream(options) {
               case "\u2028": return "\\u2028";
               case "\u2029": return "\\u2029";
               case "\ufeff": return "\\ufeff";
+              case "\uffff": return "\\uffff";
               case "\0":
                   return /[0-7]/.test(str.charAt(i+1)) ? "\\x00" : "\\0";
             }
@@ -1282,6 +1283,7 @@ function OutputStream(options) {
             0x0d   , // \r
             0x00   , // \0
             0xfeff , // Unicode BOM
+            0xffff , // Unicode noncharacter
             0x2028 , // unicode "line separator"
             0x2029 , // unicode "paragraph separator"
         ].indexOf(code) < 0;