diff --git a/package.json b/package.json
index df820de..f679220 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
     "prepublish": "./node_modules/.bin/babel -d ./lib src",
     "test": "./node_modules/.bin/mocha test/index.js --timeout 10000",
     "test-cov": "./node_modules/.bin/istanbul cover ./node_modules/mocha/bin/_mocha --report lcovonly -- -R spec && cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js && rm -rf ./coverage",
-    "gen-doc": "./node_modules/.bin/babel --no-babelrc --plugins transform-es2015-spread,transform-es2015-destructuring,transform-strict-mode,transform-es2015-parameters,transform-es2015-shorthand-properties,transform-object-rest-spread,transform-class-properties -d lib-doc src && ./node_modules/.bin/jsdoc2md --src lib-doc/telegram.js -t README.hbs > README.md",
+    "gen-doc": "./node_modules/.bin/jsdoc2md --src src/telegram.js -t README.hbs > README.md",
     "eslint": "./node_modules/.bin/eslint ./src"
   },
   "author": "Yago Pérez <yagoperezs@gmail.com>",
diff --git a/src/telegram.js b/src/telegram.js
index 6bf77f0..cd0bc5f 100644
--- a/src/telegram.js
+++ b/src/telegram.js
@@ -14,14 +14,17 @@ const URL = require('url');
 const fs = require('fs');
 const pump = require('pump');
 
+const _messageTypes = [
+  'text', 'audio', 'document', 'photo', 'sticker', 'video', 'voice', 'contact',
+  'location', 'new_chat_participant', 'left_chat_participant', 'new_chat_title',
+  'new_chat_photo', 'delete_chat_photo', 'group_chat_created'
+];
+
 class TelegramBot extends EventEmitter {
 
-  // Telegram message events
-  static messageTypes = [
-    'text', 'audio', 'document', 'photo', 'sticker', 'video', 'voice', 'contact',
-    'location', 'new_chat_participant', 'left_chat_participant', 'new_chat_title',
-    'new_chat_photo', 'delete_chat_photo', 'group_chat_created'
-  ];
+  static get messageTypes() {
+    return _messageTypes;
+  }
 
   /**
    * Both request method to obtain messages are implemented. To use standard polling, set `polling: true`
@@ -64,7 +67,7 @@ class TelegramBot extends EventEmitter {
     this._polling = new TelegramBotPolling(this.token, this.options.polling, this.processUpdate);
   }
 
-  processUpdate = (update) => {
+  processUpdate(update) {
     debug('Process Update %j', update);
     const message = update.message;
     const inlineQuery = update.inline_query;