diff --git a/Gruntfile.js b/Gruntfile.js
index b451a2d..5d0cc45 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -144,7 +144,6 @@ module.exports = function (grunt) {
         }
       },
       single: {
-        src: 'test/node/**/*.js',
         options: {
           globals: ['should'],
           timeout: 3000,
@@ -153,7 +152,7 @@ module.exports = function (grunt) {
         }
       },
       cli: {
-        src: 'test/node/testsuite.cli.js',
+        src: 'test/unit/cli.js',
         options: {
           globals: ['should'],
           timeout: 3000,
@@ -208,14 +207,12 @@ module.exports = function (grunt) {
   /**
    * Run a single test
    */
-  grunt.registerTask('single-test', function (grep) {
+  grunt.registerTask('single-test', function (file) {
     'use strict';
     grunt.config.merge({
       simplemocha: {
         single: {
-          options: {
-            grep: grep
-          }
+          src: file
         }
       }
     });
@@ -230,6 +227,7 @@ module.exports = function (grunt) {
   grunt.registerTask('test-functional', ['concat:test', 'simplemocha:functional', 'clean']);
   grunt.registerTask('test-unit', ['concat:test', 'simplemocha:unit', 'clean']);
   grunt.registerTask('test-cli', ['clean', 'lint', 'concat:test', 'simplemocha:cli', 'clean']);
+
   grunt.registerTask('performance', ['concat:test', 'performancejs', 'clean']);
   grunt.registerTask('build', ['test', 'concat:dist', 'concat:cli', 'uglify:dist', 'uglify:cli', 'endline']);
   grunt.registerTask('build-without-test', ['concat:dist', 'uglify', 'endline']);
diff --git a/dist/showdown.js b/dist/showdown.js
index 13ef529..347181b 100644
Binary files a/dist/showdown.js and b/dist/showdown.js differ
diff --git a/dist/showdown.js.map b/dist/showdown.js.map
index 1a0100f..d0b8c3b 100644
Binary files a/dist/showdown.js.map and b/dist/showdown.js.map differ
diff --git a/dist/showdown.min.js b/dist/showdown.min.js
index adb9074..671f8ca 100644
Binary files a/dist/showdown.min.js and b/dist/showdown.min.js differ
diff --git a/dist/showdown.min.js.map b/dist/showdown.min.js.map
index 4c7cdcd..2d00658 100644
Binary files a/dist/showdown.min.js.map and b/dist/showdown.min.js.map differ
diff --git a/src/helpers.js b/src/helpers.js
index 6ca54bf..ac5f1c7 100644
--- a/src/helpers.js
+++ b/src/helpers.js
@@ -363,12 +363,16 @@ showdown.helper.encodeEmailAddress = function (mail) {
 /**
  * String.prototype.repeat polyfill
  *
- * @param str
- * @param count
+ * @param {string} str
+ * @param {int} count
  * @returns {string}
  */
-function repeat (str, count) {
+showdown.helper.repeat = function (str, count) {
   'use strict';
+  // use built-in method if it's available
+  if (!showdown.helper.isUndefined(String.prototype.repeat)) {
+    return str.repeat(count);
+  }
   str = '' + str;
   if (count < 0) {
     throw new RangeError('repeat count must be non-negative');
@@ -396,7 +400,7 @@ function repeat (str, count) {
   }
   str += str.substring(0, maxCount - str.length);
   return str;
-}
+};
 
 /**
  * String.prototype.padEnd polyfill
@@ -418,7 +422,7 @@ showdown.helper.padEnd = function padEnd (str, targetLength, padString) {
   } else {
     targetLength = targetLength - str.length;
     if (targetLength > padString.length) {
-      padString += repeat(padString, targetLength / padString.length); //append to original to ensure we are longer than needed
+      padString += showdown.helper.repeat(padString, targetLength / padString.length); //append to original to ensure we are longer than needed
     }
     return String(str) + padString.slice(0,targetLength);
   }
diff --git a/test/unit/showdown.Converter.makeHtml.js b/test/unit/showdown.Converter.makeHtml.js
index 9f1591e..26a9f59 100644
--- a/test/unit/showdown.Converter.makeHtml.js
+++ b/test/unit/showdown.Converter.makeHtml.js
@@ -1,15 +1,14 @@
 /**
  * Created by Estevao on 15-01-2015.
  */
+require('source-map-support').install();
+require('chai').should();
+require('sinon');
+var showdown = require('../../.build/showdown.js');
 
 describe('showdown.Converter', function () {
   'use strict';
 
-  require('source-map-support').install();
-  require('chai').should();
-
-  var showdown = require('../../.build/showdown.js');
-
   describe('Converter.options extensions', function () {
     var runCount;
     showdown.extension('testext', function () {
diff --git a/test/unit/showdown.Converter.makeMarkdown.js b/test/unit/showdown.Converter.makeMarkdown.js
index fb85bf2..95e6e9c 100644
--- a/test/unit/showdown.Converter.makeMarkdown.js
+++ b/test/unit/showdown.Converter.makeMarkdown.js
@@ -1,15 +1,14 @@
 /**
  * Created by Estevao on 15-01-2015.
  */
+require('source-map-support').install();
+require('chai').should();
+require('sinon');
+var showdown = require('../../.build/showdown.js');
 
 describe('showdown.Converter', function () {
   'use strict';
 
-  require('source-map-support').install();
-  require('chai').should();
-  var jsdom = require('jsdom'),
-      document = new jsdom.JSDOM('', {}).window.document, // jshint ignore:line
-      showdown = require('../../.build/showdown.js');
 
   describe('makeMarkdown()', function () {
     var converter = new showdown.Converter();
@@ -18,7 +17,7 @@ describe('showdown.Converter', function () {
       var html = '<a href="/somefoo.html">a link</a>\n';
       var md   = '[a link](</somefoo.html>)';
 
-      converter.makeMarkdown(html, document).should.equal(md);
+      converter.makeMarkdown(html).should.equal(md);
     });
 
   });
diff --git a/test/unit/showdown.helpers.js b/test/unit/showdown.helpers.js
index c9e35c8..2995728 100644
--- a/test/unit/showdown.helpers.js
+++ b/test/unit/showdown.helpers.js
@@ -1,11 +1,14 @@
 /**
- * Created by Estevao on 27/01/2017.
+ * Created by Tivie on 27/01/2017.
  */
+require('source-map-support').install();
+require('chai').should();
+require('sinon');
+var showdown = require('../../.build/showdown.js');
 /*jshint expr: true*/
 /*jshint -W053 */
 /*jshint -W010 */
 /*jshint -W009 */
-var showdown = require('../../.build/showdown.js');
 
 describe('encodeEmailAddress()', function () {
   'use strict';
@@ -245,3 +248,12 @@ describe('matchRecursiveRegExp()', function () {
 
 });
 
+describe('repeat()', function () {
+  'use strict';
+  it('work produce the same output as String.prototype.repeat()', function () {
+    var str = 'foo',
+        expected = str.repeat(100),
+        actual = showdown.helper.repeat(str, 100);
+    expected.should.equal(actual);
+  });
+});
diff --git a/test/unit/showdown.js b/test/unit/showdown.js
index 64465d0..0d9cbf4 100644
--- a/test/unit/showdown.js
+++ b/test/unit/showdown.js
@@ -1,5 +1,6 @@
 require('source-map-support').install();
 require('chai').should();
+require('sinon');
 var expect = require('chai').expect,
     showdown = require('../../.build/showdown.js');