diff --git a/lib/index.js b/lib/index.js
index 3f73b858..2666290e 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -12,7 +12,12 @@ var ParserInline = require('./parser_inline');
 var LinkifyIt    = require('linkify-it');
 var mdurl        = require('mdurl');
 var punycode     = require('punycode');
+var trimRight    = require('trim-right');
 
+if (!String.prototype.trimRight) {
+  /*eslint-disable no-extend-native*/
+  String.prototype.trimRight = function () { return trimRight(this); };
+}
 
 var config = {
   'default': require('./presets/default'),
diff --git a/package.json b/package.json
index b474e308..d7a653b8 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,7 @@
     "entities": "~1.1.1",
     "linkify-it": "~1.2.0",
     "mdurl": "~1.0.1",
+    "trim-right": "^1.0.1",
     "uc.micro": "^1.0.0"
   },
   "devDependencies": {