diff --git a/lib/punycode.js b/lib/punycode.js
index 34da3ca5ad13b6..ea61fd0d39a39d 100644
--- a/lib/punycode.js
+++ b/lib/punycode.js
@@ -15,7 +15,7 @@ const delimiter = '-'; // '\x2D'
 
 /** Regular expressions */
 const regexPunycode = /^xn--/;
-const regexNonASCII = /[^\x20-\x7E]/; // unprintable ASCII chars + non-ASCII chars
+const regexNonASCII = /[^\0-\x7E]/; // non-ASCII chars
 const regexSeparators = /[\x2E\u3002\uFF0E\uFF61]/g; // RFC 3490 separators
 
 /** Error messages */
@@ -210,7 +210,7 @@ const decode = function(input) {
 		basic = 0;
 	}
 
-	for (var j = 0; j < basic; ++j) {
+	for (let j = 0; j < basic; ++j) {
 		// if it's not a basic code point
 		if (input.charCodeAt(j) >= 0x80) {
 			error('not-basic');
@@ -221,7 +221,7 @@ const decode = function(input) {
 	// Main decoding loop: start just after the last delimiter if any basic code
 	// points were copied; start at the beginning otherwise.
 
-	for (var index = basic > 0 ? basic + 1 : 0; index < inputLength; /* no final expression */) {
+	for (let index = basic > 0 ? basic + 1 : 0; index < inputLength; /* no final expression */) {
 
 		// `index` is the index of the next character to be consumed.
 		// Decode a generalized variable-length integer into `delta`,
@@ -229,7 +229,7 @@ const decode = function(input) {
 		// if we increase `i` as we go, then subtract off its starting
 		// value at the end to obtain `delta`.
 		let oldi = i;
-		for (var w = 1, k = base; /* no condition */; k += base) {
+		for (let w = 1, k = base; /* no condition */; k += base) {
 
 			if (index >= inputLength) {
 				error('invalid-input');
@@ -345,7 +345,7 @@ const encode = function(input) {
 			if (currentValue == n) {
 				// Represent delta as a generalized variable-length integer.
 				let q = delta;
-				for (var k = base; /* no condition */; k += base) {
+				for (let k = base; /* no condition */; k += base) {
 					const t = k <= bias ? tMin : (k >= bias + tMax ? tMax : k - bias);
 					if (q < t) {
 						break;
@@ -419,7 +419,7 @@ const punycode = {
 	 * @memberOf punycode
 	 * @type String
 	 */
-	'version': '2.0.0',
+	'version': '2.1.0',
 	/**
 	 * An object of methods to convert from JavaScript's internal character
 	 * representation (UCS-2) to Unicode code points, and back.