diff --git a/package.json b/package.json
index eae8327..a19154f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ssf",
-  "version": "0.6.3",
+  "version": "0.6.4",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/ssf.js b/ssf.js
index c97a6d3..2d15abe 100644
--- a/ssf.js
+++ b/ssf.js
@@ -5,7 +5,7 @@ var _strrev = function(x) { return String(x).split("").reverse().join("");};
 function fill(c,l) { return new Array(l+1).join(c); }
 function pad(v,d,c){var t=String(v);return t.length>=d?t:(fill(c||0,d-t.length)+t);}
 function rpad(v,d,c){var t=String(v);return t.length>=d?t:(t+fill(c||0,d-t.length));}
-SSF.version = '0.6.3';
+SSF.version = '0.6.4';
 /* Options */
 var opts_fmt = {};
 function fixopts(o){for(var y in opts_fmt) if(o[y]===undefined) o[y]=opts_fmt[y];}
@@ -263,15 +263,15 @@ var write_num = function(type, fmt, val) {
     return val < 0 ? "-" + write_num(type, fmt, -val) : commaify(String(Math.floor(val))) + "." + pad(rr,r[1].length,0);
   }
   if((r = fmt.match(/^#,#*,#0/))) return write_num(type,fmt.replace(/^#,#*,/,""),val);
-  if((r = fmt.match(/^([0#]+)-([0#]+)$/))) {
-    ff = write_num(type, fmt.replace(/-/,""), val);
+  if((r = fmt.match(/^([0#]+)\\?-([0#]+)$/))) {
+    ff = write_num(type, fmt.replace(/[\\-]/g,""), val);
     return ff.substr(0,ff.length - r[2].length) + "-" + ff.substr(ff.length-r[2].length);
   }
-  if((r = fmt.match(/^([0#]+)-([0#]+)-([0#]+)$/))) {
-    ff = write_num(type, fmt.replace(/-/g,""), val);
+  if((r = fmt.match(/^([0#]+)\\?-([0#]+)\\?-([0#]+)$/))) {
+    ff = write_num(type, fmt.replace(/[\\-]/g,""), val);
     return ff.substr(0,ff.length - r[2].length - r[3].length) + "-" + ff.substr(ff.length-r[2].length - r[3].length, r[2].length) + "-" + ff.substr(ff.length-r[3].length);
   }
-  if(fmt == "(###) ###-####") {
+  if(fmt.match(/\(###\) ###\\?-####/)) {
     ff = write_num(type, "##########", val);
     return "(" + ff.substr(0,3) + ") " + ff.substr(3, 3) + "-" + ff.substr(6);
   }
@@ -370,7 +370,7 @@ function eval_fmt(fmt, v, opts, flen) {
         break;
       /* Numbers */
       case '0': case '#': case '.':
-        o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1) o += c;
+        o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1 || c=='\\' && fmt[i+1] == "-" && "0#".indexOf(fmt[i+2])>-1) o += c;
         out.push({t:'n', v:o}); break;
       case '?':
         o = fmt[i]; while(fmt[++i] === c) o+=c;
diff --git a/ssf.md b/ssf.md
index 78ba8e6..0aba79d 100644
--- a/ssf.md
+++ b/ssf.md
@@ -470,12 +470,12 @@ The next few simplifications ignore leading optional sigils (`#`):
 The `Zip Code + 4` format needs to treat an interstitial hyphen as a character:
 
 ```
-  if((r = fmt.match(/^([0#]+)-([0#]+)$/))) {
-    ff = write_num(type, fmt.replace(/-/,""), val);
+  if((r = fmt.match(/^([0#]+)\\?-([0#]+)$/))) {
+    ff = write_num(type, fmt.replace(/[\\-]/g,""), val);
     return ff.substr(0,ff.length - r[2].length) + "-" + ff.substr(ff.length-r[2].length);
   }
-  if((r = fmt.match(/^([0#]+)-([0#]+)-([0#]+)$/))) {
-    ff = write_num(type, fmt.replace(/-/g,""), val);
+  if((r = fmt.match(/^([0#]+)\\?-([0#]+)\\?-([0#]+)$/))) {
+    ff = write_num(type, fmt.replace(/[\\-]/g,""), val);
     return ff.substr(0,ff.length - r[2].length - r[3].length) + "-" + ff.substr(ff.length-r[2].length - r[3].length, r[2].length) + "-" + ff.substr(ff.length-r[3].length);
   }
 ```
@@ -484,7 +484,7 @@ There's a better way to generalize the phone number and other formats in terms
 of first drawing the digits, but this selection allows for more nuance:
 
 ```
-  if(fmt == "(###) ###-####") {
+  if(fmt.match(/\(###\) ###\\?-####/)) {
     ff = write_num(type, "##########", val);
     return "(" + ff.substr(0,3) + ") " + ff.substr(3, 3) + "-" + ff.substr(6);
   }
@@ -669,12 +669,13 @@ pseudo-type `Z` is used to capture absolute time blocks:
         break;
 ```
 
-Number blocks (following the general pattern `[0#?][0#?.,E+-%]*`) are grouped together:
+Number blocks (following the general pattern `[0#?][0#?.,E+-%]*`) are grouped
+together.  Literal hyphens are swallowed as well:
 
 ```
       /* Numbers */
       case '0': case '#': case '.':
-        o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1) o += c;
+        o = c; while("0#?.,E+-%".indexOf(c=fmt[++i]) > -1 || c=='\\' && fmt[i+1] == "-" && "0#".indexOf(fmt[i+2])>-1) o += c;
         out.push({t:'n', v:o}); break;
 
 ```
@@ -1139,7 +1140,7 @@ coveralls:
 ```json>package.json
 {
   "name": "ssf",
-  "version": "0.6.3",
+  "version": "0.6.4",
   "author": "SheetJS",
   "description": "pure-JS library to format data using ECMA-376 spreadsheet Format Codes",
   "keywords": [ "format", "sprintf", "spreadsheet" ],
diff --git a/test/oddities.json b/test/oddities.json
index bcb2354..6595f88 100644
--- a/test/oddities.json
+++ b/test/oddities.json
@@ -73,7 +73,10 @@
   ],
   ["00000-0000", [941051630, "94105-1630"]],
   ["000-00-0000", [123456789, "123-45-6789"]],
+  ["00000\\-0000", [941051630, "94105-1630"]],
+  ["000\\-00\\-0000", [123456789, "123-45-6789"]],
   ["[<=9999999]###-####;(###) ###-####", [8675309, "867-5309"],[2813308004, "(281) 330-8004"]],
+  ["[<=9999999]###\\-####;(###) ###\\-####", [8675309, "867-5309"],[2813308004, "(281) 330-8004"]],
   ["[Red][<-25]General;[Blue][>25]General;[Green]General;[Yellow]General", [50, "50"],[26, "26"],[25,"25"],[1,"1"],[0,"0"],[-1,"-1"],[-25,"-25"],[-26,"26","#"],[-50,"50","#"], ["foo","foo"],["bar","bar"]],
   ["[Red][<=-25]General;[Blue][>=25]General;[Green]General;[Yellow]General", [50, "50"],[26, "26"],[25,"25"],[1,"1"],[0,"0"],[-1,"-1"],[-25,"-25"],[-26,"26","#"],[-50,"50","#"], ["foo","foo"],["bar","bar"]],
   ["[Red]General ;[Blue]General\\ ;[Green]Generalp;[Yellow]General'", [50, "50 "],[0,"0p"],[-25,"-25 "],["foo","foo'"]],