diff --git a/lib/telegrambot.js b/lib/telegrambot.js
index 8a320d4..aff9f40 100755
--- a/lib/telegrambot.js
+++ b/lib/telegrambot.js
@@ -46,9 +46,10 @@ TelegramBot.unwrap = function(cb) {
         // by passing the error object as the first parameter.
         if (!err && body && body.ok === false) err = TelegramBot.error(body.description, body.error_code, res.statusCode);
         if (!err && res.statusCode != 200) err = TelegramBot.error('HTTP status ' + res.statusCode + ' returned.', res.statusCode, res.statusCode);
-        if (err) return cb.apply(self, [err]);
-
-        cb.apply(self, [null, body.result]);
+        if(cb!=null && cb!=undefined){
+            if (err) return cb.apply(self, [err]);
+            cb.apply(self, [null, body.result]);
+        }
     }
 }