diff --git a/examples/telebot_bot/telebot_bot.py b/examples/telebot_bot/telebot_bot.py
index 7cf76cb..cd29276 100644
--- a/examples/telebot_bot/telebot_bot.py
+++ b/examples/telebot_bot/telebot_bot.py
@@ -42,10 +42,10 @@ def on_user_joins(message):
         return
 
     name = message.new_chat_participant.first_name
-    if hasattr(message.new_chat_participant, 'last_name'):
+    if hasattr(message.new_chat_participant, 'last_name') and message.new_chat_participant.last_name is not None:
         name += u" {}".format(message.new_chat_participant.last_name)
 
-    if hasattr(message.new_chat_participant, 'username'):
+    if hasattr(message.new_chat_participant, 'username') and message.new_chat_participant.username is not None:
         name += u" (@{})".format(message.new_chat_participant.username)
 
     bot.reply_to(message, text_messages['welcome'].format(name=name))