diff --git a/Makefile b/Makefile
index 38e6a7e..ab71f88 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@ stress:
 	@make -C stress test
 
 .PHONY: clean-stress
-clean-stress: ## Remove stress tests 
+clean-stress: ## Remove stress tests
 	@make -C stress clean
 
 ## Code Checking
diff --git a/README.md b/README.md
index d4a69c9..ddfa651 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # printj
 
 Extended `sprintf` implementation (for the browser and nodejs).  Emphasis on
-compliance and performance.
+compliance, performance and IE6+ support.
 
 ```JS
 PRINTJ.sprintf("Hello %s!", "World");
@@ -15,11 +15,15 @@ A self-contained specification of the printf format string is included below in
 
 With [npm](https://www.npmjs.org/package/printj):
 
-    $ npm install printj
+```bash
+$ npm install printj
+```
 
 In the browser:
 
-    <script src="printj.js"></script>
+```html
+<script src="printj.js"></script>
+```
 
 The browser exposes a variable `PRINTJ`
 
@@ -44,7 +48,7 @@ For example:
 
 ```js
 > // var PRINTJ = require('printj');       // uncomment this line if in node
-> var sprintf = PRINTJ.sprintf, vsprintf = PRINTJ.vsprintf; 
+> var sprintf = PRINTJ.sprintf, vsprintf = PRINTJ.vsprintf;
 > sprintf("Hello %s", "SheetJS")           // 'Hello SheetJS'
 > sprintf("%d + %d = %d", 2,3,2+3)         // '2 + 3 = 5'
 > vsprintf("%d + %d = %d", [2,3,5])        // '2 + 3 = 5'
@@ -87,7 +91,7 @@ requires access to a C compiler.
 Please consult the attached LICENSE file for details.  All rights not explicitly
 granted by the Apache 2.0 license are reserved by the Original Author.
 
-## Badges 
+## Badges
 
 [![Build Status](https://travis-ci.org/SheetJS/printj.svg?branch=master)](https://travis-ci.org/SheetJS/printj)
 
@@ -137,7 +141,7 @@ int vswprintf(wchar_t *ostr, const wchar_t *fmt, va_list arg_list);
 
 C "strings" are really just arrays of numbers.  An external code page (such as
 ASCII) maps those numbers to characters.  K&R defines two types of strings:
-basic character set strings (`char *`) and extended character set strings 
+basic character set strings (`char *`) and extended character set strings
 (`wchar_t *`). In contrast, JS has a true string value type.
 
 Unlike in C, JS strings do not treat the null character as an end-of-string
@@ -439,7 +443,7 @@ K&R "printable characters are always positive", the types are assumed unsigned.
 
 K&R recognizes 3 floating point types.  C99 later tied it to IEC 60559:
 
-|  C data type  | precision | total bits | exponent | mantissa |  fmt  | 
+|  C data type  | precision | total bits | exponent | mantissa |  fmt  |
 |:--------------|:----------|:----------:|:--------:|:--------:|------:|
 | `float`       | single    |    `32`    |    `8`   |   `23`   |       |
 | `double`      | double    |    `64`    |   `11`   |   `52`   |   `f` |
@@ -543,36 +547,36 @@ is signed or unsigned according to the conversion specifier.  If a length is
 specified, it overrides the implied length of the conversion.  The following
 table describes the behavior of this implementation:
 
-| implied C type                      | ctypes.json | length | conv default | 
+| implied C type                      | ctypes.json | length | conv default |
 |:------------------------------------|:------------|:------:|:-------------|
 | `int` or `unsigned int`             | `int`       | (none) | d i o u x X  |
 | `char` or `unsigned char`           | `char`      |   hh   |
 | `short` or `unsigned short`         | `short`     |    h   |
 | `long` or `unsigned long`           | `long`      |    l   | D U O        |
-| `long long` or `unsigned long long` | `longlong`  | L ll q | 
+| `long long` or `unsigned long long` | `longlong`  | L ll q |
 | `intmax_t` or `uintmax_t`           | `intmax_t`  |    j   |
 | `size_t` or `ssize_t`               | `size_t`    |   z Z  |
 | `ptrdiff_t` or unsigned variant     | `ptrdiff_t` |    t   |
 
 ## Rendering Unsigned Integers in Base 10 ("u" and "U" conversions)
 
-`num.toString(10)` produces the correct result for exact integers.  
+`num.toString(10)` produces the correct result for exact integers.
 
-`"u"` conversion restricts values to `int`; `"U"` restricts to `long`. 
+`"u"` conversion restricts values to `int`; `"U"` restricts to `long`.
 
 ## Rendering Unsigned Integers in Base 8 ("o" and "O" conversions)
 
 Even though `num.toString(8)` is implementation-dependent, all browser
-implementations use standard form for integers in the exact range. 
+implementations use standard form for integers in the exact range.
 
 The alternate form (`#`) prints a `"0"` prefix.
 
-`"o"` conversion restricts values to `int`; `"O"` restricts to `long`. 
+`"o"` conversion restricts values to `int`; `"O"` restricts to `long`.
 
 ## Rendering Unsigned Integers in Base 16 ("x" and "X" conversions)
 
 Even though `num.toString(16)` is implementation-dependent, all browser
-implementations use standard form for integers in the exact range. 
+implementations use standard form for integers in the exact range.
 
 The alternate form (`#`) prints a `"0x"` or `"0X"` prefix.
 
@@ -583,7 +587,7 @@ Unlike `"U" "O" "D"`, `"X"` conversion uses `A-F` instead of `a-f` in hex.
 `num.toString(10)` produces the correct result for exact integers.  The flags
 `" +"` control prefixes for positive integers.
 
-`"di"` conversions restrict values to `int`; `"D"` restricts to `long`. 
+`"di"` conversions restrict values to `int`; `"D"` restricts to `long`.
 
 
 # Floating Point Conversions
@@ -678,7 +682,7 @@ JS `num.toString(radix)` is implementation-dependent for valid non-10 radices
 (`2-9, 11-36`).  IE uses hex-mantissa decimal-hex-exponent form when the
 absolute value of the base-2 exponent exceeds 60.  Otherwise, IE uses an exact
 standard hexadecimal form.  Chrome, Safari and other browsers always use the
-exact standard hexadecimal form.  Both forms are easily converted to `"%a"` by 
+exact standard hexadecimal form.  Both forms are easily converted to `"%a"` by
 calculating and dividing by the appropriate power of 2.
 
 For each non-zero normal floating point value, there are 4 acceptable strings
@@ -695,7 +699,7 @@ of 2 and adjusting the exponent accordingly:
 JS engines follow the glibc model: multiply by a suitable power of 16 so that
 the mantissa is between 1 and 16, render left to right one digit at a time, then
 fix the result at the end.  FreeBSD and OSX always show the normalized form.
-This implementation defaults to the normalized form.  To switch to the glibc 
+This implementation defaults to the normalized form.  To switch to the glibc
 form, define `DO_NOT_NORMALIZE` in the `JSFLAGS` variable when building:
 
 ```bash
@@ -958,7 +962,7 @@ JS.  When converting C literal strings, there are a few differences in escaping:
 
 | C escape sequence | Equivalent JS | Notes                                  |
 |:------------------|:--------------|:---------------------------------------|
-| `"\a"`            |  `"\007"`     | BEL character will not ring in browser | 
+| `"\a"`            |  `"\007"`     | BEL character will not ring in browser |
 | `"\?"`            |  `"?"`        | JS does not handle trigraphs           |
 | `"\ooo"` (octal)  |  `"\ooo"`     | JS uses Latin-1 for non-ASCII codes    |
 | `"\xhh"` (hex)    |  `"\xhh"`     | JS uses Latin-1 for non-ASCII codes    |
@@ -970,7 +974,7 @@ JS.  When converting C literal strings, there are a few differences in escaping:
 - Full support for POSIX flags and positional parameters
 - Emulation of BSD `quad_t` and `u_quad_t` conversion
 - Parser accepts but does not emulate CRT wide and unicode character conversions
-- glibc `Z` length conversion and extended `m` error support 
-- CRT `I/w` length but no `I32/I64`
+- glibc `Z` length conversion and extended `m` error support
+- Parser fails on CRT `I32`/`I64` fixed lengths
 - Default `LP64` data model but can be configured to support `ILP32` or `LLP64`
 
diff --git a/bits/01_version.js b/bits/01_version.js
index d2ecaff..3975aef 100644
--- a/bits/01_version.js
+++ b/bits/01_version.js
@@ -1 +1 @@
-PRINTJ.version = '0.1.0';
+PRINTJ.version = '0.1.1';
diff --git a/bits/40_macros.js b/bits/40_macros.js
index 9611fd9..df7be1a 100644
--- a/bits/40_macros.js
+++ b/bits/40_macros.js
@@ -11,7 +11,7 @@ var padstr = {
 function pads(x/*:number*/, c/*:string*/)/*:string*/ { return PAD_(x,c); }
 #define PADS(x,c) pads(x,c)
 #else
-#define PADS(x,c) PAD_(x,c) 
+#define PADS(x,c) PAD_(x,c)
 #endif
 
 #define PAD(x)    pad = PADS(x, " ")
@@ -41,11 +41,11 @@ function pads(x/*:number*/, c/*:string*/)/*:string*/ { return PAD_(x,c); }
 
 #if SIZEOF_SIZE_T > 4 /* TODO: negative ptrs? */
 #define CONV_SIZE_T(x) x = Math.abs(x);
-#define SIZE_T_TO_HEX(n) n.toString(16) 
+#define SIZE_T_TO_HEX(n) n.toString(16)
 #else
 #define CONV_SIZE_T(x) x = (x>>>0);
 #define SIZE_T_TO_HEX(n) n.toString(16)
-#endif 
+#endif
 
 
 #define IDX_POS 2
diff --git a/bits/54_convmisc.js b/bits/54_convmisc.js
index f024592..e146433 100644
--- a/bits/54_convmisc.js
+++ b/bits/54_convmisc.js
@@ -1,6 +1,6 @@
 			/* JS has no concept of pointers so interpret the `l` key as an address */
 			case /*p*/ 112:
-				Vnum = typeof arg == "number" ? arg : Number(arg.l);
+				Vnum = typeof arg == "number" ? arg : arg ? Number(arg.l) : -1;
 				if(isnan(Vnum)) Vnum = -1;
 				if(alt) O = Vnum.toString(10);
 				else {
@@ -24,7 +24,7 @@
 
 			/* JS-specific conversions (extension) */
 			case /*J*/  74: O = (alt ? u_inspect : JSON.stringify)(arg); break;
-			case /*V*/  86: O = String(arg.valueOf()); break;
+			case /*V*/  86: O = arg == null ? "null" : String(arg.valueOf()); break;
 			case /*T*/  84:
 				if(alt) { /* from '[object %s]' extract %s */
 					O = Object.prototype.toString.call(arg).substr(8);
diff --git a/bits/60_integer.js b/bits/60_integer.js
index 75fa275..4d8c367 100644
--- a/bits/60_integer.js
+++ b/bits/60_integer.js
@@ -9,7 +9,7 @@
 				case 1: _DOIT(0xFF, 0x7F); break;
 				case 2: _DOIT(0xFFFF, 0x7FFF); break;
 				case 4: Vnum = sign ? (Vnum | 0) : (Vnum >>> 0); break;
-				default: Vnum = Math.round(Vnum); break;
+				default: Vnum = isnan(Vnum) ? 0 : Math.round(Vnum); break;
 			}
 #undef _DOIT
 
diff --git a/bits/70_float.js b/bits/70_float.js
index e55d516..328dbd3 100644
--- a/bits/70_float.js
+++ b/bits/70_float.js
@@ -1,4 +1,5 @@
 			Vnum = Number(arg);
+			if(arg === null) Vnum = 0/0;
 			if(len == "L") bytes = 12;
 			var isf = isFinite(Vnum);
 			if(!isf) { /* Infinity or NaN */
@@ -27,7 +28,7 @@
 				switch(isnum) {
 					/* f/F standard */
 					case 1: case 11:
-						if(Vnum < Math.pow(10,21)) {
+						if(Vnum < 1e21) {
 							O = Vnum.toFixed(prec);
 							if(isnum == 1) { if(prec===0 &&alt&& O.indexOf(".")==-1) O+="."; }
 							else if(!alt) O=O.replace(/(\.\d*[1-9])0*$/,"$1").replace(/\.0*$/,"");
diff --git a/index.html b/index.html
index 51f3db5..b1e0159 100644
--- a/index.html
+++ b/index.html
@@ -27,6 +27,8 @@ This implementation supports the full POSIX set of conversions.  Consult the enc
 <tr><th>example</th><th>result</th></tr>
 </table>
 <script type="text/javascript">/* jshint browser:true, evil:true */</script>
+<script src="shim.js"></script>
+<script src="http://cdnjs.cloudflare.com/ajax/libs/json3/3.3.2/json3.min.js"></script>
 <script src="printj.js"></script>
 <script type="text/javascript">
 var table = document.getElementById("data");
diff --git a/package.json b/package.json
index 53cc436..3e23a87 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "printj",
-	"version": "0.1.0",
+	"version": "0.1.1",
 	"author": "sheetjs",
 	"description": "Pure-JS printf",
 	"keywords": [ "printf", "sprintf", "format", "string" ],
diff --git a/printj.flow.js b/printj.flow.js
index 09e2e66..f0d0f48 100644
--- a/printj.flow.js
+++ b/printj.flow.js
@@ -26,7 +26,7 @@ var PRINTJ/*:any*/;
 	/*jshint ignore:end */
 }(function(PRINTJ) {
 
-PRINTJ.version = '0.1.0';
+PRINTJ.version = '0.1.1';
 
 function tokenize(fmt/*:string*/)/*:ParsedFmt*/ {
 	var out/*:ParsedFmt*/ = [];
@@ -275,7 +275,7 @@ function doit(t/*:ParsedFmt*/, args/*:Array<any>*/)/*:string*/ {
 
 			/* JS has no concept of pointers so interpret the `l` key as an address */
 			case /*p*/ 112:
-				Vnum = typeof arg == "number" ? arg : Number(arg.l);
+				Vnum = typeof arg == "number" ? arg : arg ? Number(arg.l) : -1;
 				if(isNaN(Vnum)) Vnum = -1;
 				if(alt) O = Vnum.toString(10);
 				else {
@@ -299,7 +299,7 @@ function doit(t/*:ParsedFmt*/, args/*:Array<any>*/)/*:string*/ {
 
 			/* JS-specific conversions (extension) */
 			case /*J*/  74: O = (alt ? u_inspect : JSON.stringify)(arg); break;
-			case /*V*/  86: O = String(arg.valueOf()); break;
+			case /*V*/  86: O = arg == null ? "null" : String(arg.valueOf()); break;
 			case /*T*/  84:
 				if(alt) { /* from '[object %s]' extract %s */
 					O = Object.prototype.toString.call(arg).substr(8);
@@ -365,7 +365,7 @@ function doit(t/*:ParsedFmt*/, args/*:Array<any>*/)/*:string*/ {
 				case 1: Vnum = (Vnum & 0xFF); if(sign && (Vnum >  0x7F)) Vnum -= (0xFF + 1); break;
 				case 2: Vnum = (Vnum & 0xFFFF); if(sign && (Vnum >  0x7FFF)) Vnum -= (0xFFFF + 1); break;
 				case 4: Vnum = sign ? (Vnum | 0) : (Vnum >>> 0); break;
-				default: Vnum = Math.round(Vnum); break;
+				default: Vnum = isNaN(Vnum) ? 0 : Math.round(Vnum); break;
 			}
 
 			/* generate string */
@@ -444,6 +444,7 @@ function doit(t/*:ParsedFmt*/, args/*:Array<any>*/)/*:string*/ {
 		} else if(isnum > 0) {
 
 			Vnum = Number(arg);
+			if(arg === null) Vnum = 0/0;
 			if(len == "L") bytes = 12;
 			var isf = isFinite(Vnum);
 			if(!isf) { /* Infinity or NaN */
@@ -472,7 +473,7 @@ function doit(t/*:ParsedFmt*/, args/*:Array<any>*/)/*:string*/ {
 				switch(isnum) {
 					/* f/F standard */
 					case 1: case 11:
-						if(Vnum < Math.pow(10,21)) {
+						if(Vnum < 1e21) {
 							O = Vnum.toFixed(prec);
 							if(isnum == 1) { if(prec===0 &&alt&& O.indexOf(".")==-1) O+="."; }
 							else if(!alt) O=O.replace(/(\.\d*[1-9])0*$/,"$1").replace(/\.0*$/,"");
diff --git a/printj.js b/printj.js
index cda411d..0371c14 100644
--- a/printj.js
+++ b/printj.js
@@ -24,7 +24,7 @@ var PRINTJ;
 	/*jshint ignore:end */
 }(function(PRINTJ) {
 
-PRINTJ.version = '0.1.0';
+PRINTJ.version = '0.1.1';
 
 function tokenize(fmt) {
 	var out = [];
@@ -271,7 +271,7 @@ function doit(t, args) {
 
 			/* JS has no concept of pointers so interpret the `l` key as an address */
 			case /*p*/ 112:
-				Vnum = typeof arg == "number" ? arg : Number(arg.l);
+				Vnum = typeof arg == "number" ? arg : arg ? Number(arg.l) : -1;
 				if(isNaN(Vnum)) Vnum = -1;
 				if(alt) O = Vnum.toString(10);
 				else {
@@ -295,7 +295,7 @@ function doit(t, args) {
 
 			/* JS-specific conversions (extension) */
 			case /*J*/  74: O = (alt ? u_inspect : JSON.stringify)(arg); break;
-			case /*V*/  86: O = String(arg.valueOf()); break;
+			case /*V*/  86: O = arg == null ? "null" : String(arg.valueOf()); break;
 			case /*T*/  84:
 				if(alt) { /* from '[object %s]' extract %s */
 					O = Object.prototype.toString.call(arg).substr(8);
@@ -361,7 +361,7 @@ function doit(t, args) {
 				case 1: Vnum = (Vnum & 0xFF); if(sign && (Vnum >  0x7F)) Vnum -= (0xFF + 1); break;
 				case 2: Vnum = (Vnum & 0xFFFF); if(sign && (Vnum >  0x7FFF)) Vnum -= (0xFFFF + 1); break;
 				case 4: Vnum = sign ? (Vnum | 0) : (Vnum >>> 0); break;
-				default: Vnum = Math.round(Vnum); break;
+				default: Vnum = isNaN(Vnum) ? 0 : Math.round(Vnum); break;
 			}
 
 			/* generate string */
@@ -440,6 +440,7 @@ function doit(t, args) {
 		} else if(isnum > 0) {
 
 			Vnum = Number(arg);
+			if(arg === null) Vnum = 0/0;
 			if(len == "L") bytes = 12;
 			var isf = isFinite(Vnum);
 			if(!isf) { /* Infinity or NaN */
@@ -468,7 +469,7 @@ function doit(t, args) {
 				switch(isnum) {
 					/* f/F standard */
 					case 1: case 11:
-						if(Vnum < Math.pow(10,21)) {
+						if(Vnum < 1e21) {
 							O = Vnum.toFixed(prec);
 							if(isnum == 1) { if(prec===0 &&alt&& O.indexOf(".")==-1) O+="."; }
 							else if(!alt) O=O.replace(/(\.\d*[1-9])0*$/,"$1").replace(/\.0*$/,"");
diff --git a/shim.js b/shim.js
new file mode 100644
index 0000000..e3d7840
--- /dev/null
+++ b/shim.js
@@ -0,0 +1,237 @@
+// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
+if (!Object.keys) {
+  Object.keys = (function () {
+    var hasOwnProperty = Object.prototype.hasOwnProperty,
+        hasDontEnumBug = !({toString: null}).propertyIsEnumerable('toString'),
+        dontEnums = [
+          'toString',
+          'toLocaleString',
+          'valueOf',
+          'hasOwnProperty',
+          'isPrototypeOf',
+          'propertyIsEnumerable',
+          'constructor'
+        ],
+        dontEnumsLength = dontEnums.length;
+
+    return function (obj) {
+      if (typeof obj !== 'object' && typeof obj !== 'function' || obj === null) throw new TypeError('Object.keys called on non-object');
+
+      var result = [];
+
+      for (var prop in obj) {
+        if (hasOwnProperty.call(obj, prop)) result.push(prop);
+      }
+
+      if (hasDontEnumBug) {
+        for (var i=0; i < dontEnumsLength; i++) {
+          if (hasOwnProperty.call(obj, dontEnums[i])) result.push(dontEnums[i]);
+        }
+      }
+      return result;
+    };
+  })();
+}
+
+// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
+if (!Array.prototype.filter)
+{
+  Array.prototype.filter = function(fun /*, thisp */)
+  {
+    "use strict";
+
+    if (this == null)
+      throw new TypeError();
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (typeof fun != "function")
+      throw new TypeError();
+
+    var res = [];
+    var thisp = arguments[1];
+    for (var i = 0; i < len; i++)
+    {
+      if (i in t)
+      {
+        var val = t[i]; // in case fun mutates this
+        if (fun.call(thisp, val, i, t))
+          res.push(val);
+      }
+    }
+
+    return res;
+  };
+}
+
+// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim
+if (!String.prototype.trim) {
+  String.prototype.trim = function () {
+    return this.replace(/^\s+|\s+$/g, '');
+  };
+}
+
+// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
+if (!Array.prototype.forEach)
+{
+  Array.prototype.forEach = function(fun /*, thisArg */)
+  {
+    "use strict";
+
+    if (this === void 0 || this === null)
+      throw new TypeError();
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (typeof fun !== "function")
+      throw new TypeError();
+
+    var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
+    for (var i = 0; i < len; i++)
+    {
+      if (i in t)
+        fun.call(thisArg, t[i], i, t);
+    }
+  };
+}
+
+// Production steps of ECMA-262, Edition 5, 15.4.4.19
+// Reference: http://es5.github.com/#x15.4.4.19
+if (!Array.prototype.map) {
+  Array.prototype.map = function(callback, thisArg) {
+
+    var T, A, k;
+
+    if (this == null) {
+      throw new TypeError(" this is null or not defined");
+    }
+
+    // 1. Let O be the result of calling ToObject passing the |this| value as the argument.
+    var O = Object(this);
+
+    // 2. Let lenValue be the result of calling the Get internal method of O with the argument "length".
+    // 3. Let len be ToUint32(lenValue).
+    var len = O.length >>> 0;
+
+    // 4. If IsCallable(callback) is false, throw a TypeError exception.
+    // See: http://es5.github.com/#x9.11
+    if (typeof callback !== "function") {
+      throw new TypeError(callback + " is not a function");
+    }
+
+    // 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
+    if (thisArg) {
+      T = thisArg;
+    }
+
+    // 6. Let A be a new array created as if by the expression new Array(len) where Array is
+    // the standard built-in constructor with that name and len is the value of len.
+    A = new Array(len);
+
+    // 7. Let k be 0
+    k = 0;
+
+    // 8. Repeat, while k < len
+    while(k < len) {
+
+      var kValue, mappedValue;
+
+      // a. Let Pk be ToString(k).
+      //   This is implicit for LHS operands of the in operator
+      // b. Let kPresent be the result of calling the HasProperty internal method of O with argument Pk.
+      //   This step can be combined with c
+      // c. If kPresent is true, then
+      if (k in O) {
+
+        // i. Let kValue be the result of calling the Get internal method of O with argument Pk.
+        kValue = O[ k ];
+
+        // ii. Let mappedValue be the result of calling the Call internal method of callback
+        // with T as the this value and argument list containing kValue, k, and O.
+        mappedValue = callback.call(T, kValue, k, O);
+
+        // iii. Call the DefineOwnProperty internal method of A with arguments
+        // Pk, Property Descriptor {Value: mappedValue, : true, Enumerable: true, Configurable: true},
+        // and false.
+
+        // In browsers that support Object.defineProperty, use the following:
+        // Object.defineProperty(A, Pk, { value: mappedValue, writable: true, enumerable: true, configurable: true });
+
+        // For best browser support, use the following:
+        A[ k ] = mappedValue;
+      }
+      // d. Increase k by 1.
+      k++;
+    }
+
+    // 9. return A
+    return A;
+  };
+}
+
+// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
+if (!Array.prototype.indexOf) {
+  Array.prototype.indexOf = function (searchElement, fromIndex) {
+    if ( this === undefined || this === null ) {
+      throw new TypeError( '"this" is null or not defined' );
+    }
+
+    var length = this.length >>> 0; // Hack to convert object.length to a UInt32
+
+    fromIndex = +fromIndex || 0;
+
+    if (Math.abs(fromIndex) === Infinity) {
+      fromIndex = 0;
+    }
+
+    if (fromIndex < 0) {
+      fromIndex += length;
+      if (fromIndex < 0) {
+        fromIndex = 0;
+      }
+    }
+
+    for (;fromIndex < length; fromIndex++) {
+      if (this[fromIndex] === searchElement) {
+        return fromIndex;
+      }
+    }
+
+    return -1;
+  };
+}
+// Based on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
+
+if (! Array.isArray) {
+    Array.isArray = function(obj) {
+        return Object.prototype.toString.call(obj) === "[object Array]";
+    };
+}
+
+// https://github.com/ttaubert/node-arraybuffer-slice
+// (c) 2013 Tim Taubert <tim@timtaubert.de>
+// arraybuffer-slice may be freely distributed under the MIT license.
+
+"use strict";
+
+if (typeof ArrayBuffer !== 'undefined' && !ArrayBuffer.prototype.slice) {
+  ArrayBuffer.prototype.slice = function (begin, end) {
+    begin = (begin|0) || 0;
+    var num = this.byteLength;
+    end = end === (void 0) ? num : (end|0);
+
+    // Handle negative values.
+    if (begin < 0) begin += num;
+    if (end < 0) end += num;
+
+    if (num === 0 || begin >= num || begin >= end) {
+      return new ArrayBuffer(0);
+    }
+
+    var length = Math.min(num - begin, end - begin);
+    var target = new ArrayBuffer(length);
+    var targetArray = new Uint8Array(target);
+    targetArray.set(new Uint8Array(this, begin, length));
+    return target;
+  };
+}
diff --git a/stress/Makefile b/stress/Makefile
index 78945e0..6bb4a9f 100644
--- a/stress/Makefile
+++ b/stress/Makefile
@@ -17,7 +17,7 @@ stress.h: generate_stress.njs
 stress: stress.c stress.h tests.h
 	gcc $(CPPFLAGS) -o $@ $<
 
-stress.njs: stress.js stress.h tests.h 
+stress.njs: stress.js stress.h tests.h
 	cpp -DJAVASCRIPT $(FLAGS) $< > $@
 
 .PHONY: test
diff --git a/stress/generate_stress.njs b/stress/generate_stress.njs
index 09dd9cb..d3591d3 100644
--- a/stress/generate_stress.njs
+++ b/stress/generate_stress.njs
@@ -51,7 +51,7 @@ function getarg(format/*:string*/, length/*:string*/)/*:string*/ {
 	switch(type) {
 		case 's': return "ws";
 		case 'd': if(length == "L") return "ld";
-		case 'i': case 'u': return length + type; 
+		case 'i': case 'u': return length + type;
 	}
 	return type;
 }
diff --git a/test.js b/test.js
index 26ce659..f517020 100644
--- a/test.js
+++ b/test.js
@@ -37,3 +37,109 @@ describe('correctness', function() {
 		});
 	});
 });
+
+var sprintf = IMPLS["base"].sprintf;
+var chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ !\"#$%&'()*+,-./0123456789:;<=>?@[\\]^_~{|}`".split("");
+var convs = "aAbBcCdDeEfFgGiJmnoOpsSTuUVxXyY%".split("");
+var flags = " #'+-0".split("");
+var digits = "0123456789".split("");
+var lens = "hIjlLqtwzZ".split(""); lens.push("hh"); lens.push("ll");
+var other = "$*.".split("");
+var unused = []; chars.forEach(function(c) {
+	if(convs.indexOf(c) == -1  &&
+	   flags.indexOf(c) == -1  &&
+	   digits.indexOf(c) == -1 &&
+	   lens.indexOf(c) == -1   &&
+	   other.indexOf(c) == -1
+	) unused.push(c);
+});
+
+describe('special cases', function() {
+	it('fails on unrecognized format chars: ' + unused.join(""), function() {
+		unused.forEach(function(c) {
+			assert.throws(function() { sprintf("%" + c, 0); }, "Should fail on %" +c);
+		});
+	});
+	it('accepts all expected conversions: ' + convs.join(""), function() {
+		convs.forEach(function(c) {
+			assert.doesNotThrow(function() { sprintf("%" + c, 0); }, "Should pass on %" +c);
+		});
+	});
+	it('accepts all expected lengths: ' + lens.join(""), function() {
+		lens.forEach(function(l) {
+			var fmt = "%" + l + "X";
+			assert.doesNotThrow(function() { sprintf(fmt, 0); }, "Should pass on "+fmt);
+		});
+	});
+	it('accepts all expected flags: ' + flags.join(""), function() {
+		flags.forEach(function(l) {
+			var fmt = "%" + l + "X";
+			assert.doesNotThrow(function() { sprintf(fmt, 0); }, "Should pass on "+fmt);
+		});
+	});
+	it('correctly handles character conversions: cC', function() {
+		assert.equal(sprintf("|%c %c|", "69", 69), "|6 E|");
+		assert.equal(sprintf("|%c|", {toString:function() { return "69"; }, valueOf: function() { return 69; }} ), "|6|");
+	});
+	it('correctly handles error conversion: m', function() {
+		var x = new Error("sheetjs");
+		x.errno = 69; x.toString = function() { return "SHEETJS"; };
+		assert.equal(sprintf("|%#m|", x), "|sheetjs|");
+		delete x.message;
+		assert.equal(sprintf("|%#m|", x), "|Error number 69|");
+		delete x.errno;
+		assert.equal(sprintf("|%#m|", x), "|Error SHEETJS|");
+	});
+	it('correctly handles typeof and valueOf conversions: TV', function() {
+		assert.equal(sprintf("%1$T %1$#T", 1), 'number Number');
+		assert.equal(sprintf("%1$T %1$#T", 'foo'), 'string String');
+		assert.equal(sprintf("%1$T %1$#T", [1,2,3]), 'object Array');
+		assert.equal(sprintf("%1$T %1$#T", null), 'object Null');
+		assert.equal(sprintf("%1$T %1$#T", undefined), 'undefined Undefined');
+
+		var _f = function() { return "f"; };
+		var _3 = function() { return 3; };
+		assert.equal(sprintf("%1$d %1$s %1$V", {toString:_f}), '0 f f');
+		assert.equal(sprintf("%1$d %1$s %1$V", {valueOf:_3}), '3 [object Object] 3');
+		assert.equal(sprintf("%1$d %1$s %1$V", {valueOf:_3, toString:_f}), '3 f 3');
+	});
+	it('correctly handles standard integer conversions: diouxXDUO', function() {
+		assert.equal(sprintf("%02hhx %02hhX", 1, 1234321), "01 91");
+		assert.equal(sprintf("%02hhx %-02hhX", -1, -253), "ff 3 ");
+		assert.equal(sprintf("%#02llx", -3), "0xfffffffffffffffd");
+		assert.equal(sprintf("%#02llX", -3), "0XFFFFFFFFFFFFFFFD");
+		assert.equal(sprintf("%#02llo", -3), "01777777777777777777775");
+		assert.equal(sprintf("%#02llu", -3), "18446744073709551613");
+		assert.equal(sprintf("%#03lld", -3), "-03");
+		assert.equal(sprintf("%.9d %.9d", 123456, -123456), "000123456 -000123456");
+	});
+	it('correctly handles new binary conversions: bB', function() {
+		assert.equal(sprintf("%#b", -3), "0b11111111111111111111111111111101");
+		assert.equal(sprintf("%#5B", 3), " 0b11");
+	});
+	it('recognizes IEEE754 special values', function() {
+		assert.equal(sprintf("%a", Infinity), "inf");
+		assert.equal(sprintf("%e", -Infinity), "-inf");
+		assert.equal(sprintf("%f", 0/0), "nan");
+		assert.equal(sprintf("%g", 1/-Infinity), "-0");
+	});
+	it('correctly handles floating point conversions: aAeEfFgG', function() {
+		assert.equal(sprintf("%1$g %1$#g", 1e5), "100000 100000.");
+		assert.equal(sprintf("%.3g %.3g", 1.2345e-4, 1.2345e-5), "0.000123 1.23e-05");
+		assert.equal(sprintf("%f", 1.23e22), "12300000000000001048600.000000");
+		assert.equal(sprintf("%a %A %a %A", 1, .2, .69, 6e20), "0x1p+0 0X1.999999999999AP-3 0x1.6147ae147ae14p-1 0X1.043561A88293P+69");
+		assert.equal(sprintf("%La %LA %La %LA", 1, .2, .69, 6e20), "0x8p-3 0XC.CCCCCCCCCCCDP-6 0xb.0a3d70a3d70ap-4 0X8.21AB0D441498P+66");
+		assert.equal(sprintf("|%1$4.1f|%1$04.1f|%1$-4.1f", 1.2), "| 1.2|01.2|1.2 ");
+		assert.equal(sprintf("%1$.1a|%1$04.0f", -128), "-0x1.0p+7|-128");
+		assert.equal(sprintf("%1$.1a|%1$04.0f", -6.9e-11), "-0x1.3p-34|-000");
+		assert.equal(sprintf("%010.1a", 1.), "0x001.0p+0");
+		assert.equal(sprintf("%.7a %.7a", 129, -129), "0x1.0200000p+7 -0x1.0200000p+7");
+		assert.equal(sprintf("%.7a", -3.1), "-0x1.8cccccdp+1");
+	});
+	it('consistently handles null and undefined', function() {
+		assert.equal(sprintf("|%1$a|%1$A|%1$e|%1$E|%1$f|%1$F|%1$g|%1$G|", undefined), "|nan|NAN|nan|NAN|nan|NAN|nan|NAN|");
+		assert.equal(sprintf("|%1$a|%1$A|%1$e|%1$E|%1$f|%1$F|%1$g|%1$G|", null), "|nan|NAN|nan|NAN|nan|NAN|nan|NAN|");
+		assert.equal(sprintf("|%1$b|%1$B|%1$d|%1$D|%1$i|%1$o|%1$O|%1$u|%1$U|%1$x|%1$X|", undefined), "|0|0|0|0|0|0|0|0|0|0|0|");
+		assert.equal(sprintf("|%1$b|%1$B|%1$d|%1$D|%1$i|%1$o|%1$O|%1$u|%1$U|%1$x|%1$X|", null), "|0|0|0|0|0|0|0|0|0|0|0|");
+	});
+});
diff --git a/tests/printf.js b/tests/printf.js
index 6bf61f6..ada68ee 100644
--- a/tests/printf.js
+++ b/tests/printf.js
@@ -89865,7 +89865,7 @@ var tests = [
 	[["|%05.2Y|", 1], "|000TR|"],
 	[["|%-5.2y|", 0], "|fa   |"],
 
-	// typeof 
+	// typeof
 	[["|%1$T %1$#T|", 0], "|number Number|"],
 	[["|%1$T %1$#T|", 'foo'], "|string String|"],
 	[["|%1$T %1$#T|", [1,2,3]], "|object Array|"],