diff --git a/telebot/__init__.py b/telebot/__init__.py
index f151195..4f59e04 100644
--- a/telebot/__init__.py
+++ b/telebot/__init__.py
@@ -1239,7 +1239,7 @@ class TeleBot:
         """
         return apihelper.pin_chat_message(self.token, chat_id, message_id, disable_notification)
 
-    def unpin_chat_message(self, chat_id, message_id):
+    def unpin_chat_message(self, chat_id, message_id=None):
         """
         Use this method to unpin specific pinned message in a supergroup chat.
         The bot must be an administrator in the chat for this to work and must have the appropriate admin rights.
diff --git a/telebot/apihelper.py b/telebot/apihelper.py
index b43d341..1cc57ab 100644
--- a/telebot/apihelper.py
+++ b/telebot/apihelper.py
@@ -830,7 +830,7 @@ def pin_chat_message(token, chat_id, message_id, disable_notification=None):
     return _make_request(token, method_url, params=payload, method='post')
 
 
-def unpin_chat_message(token, chat_id, message_id):
+def unpin_chat_message(token, chat_id, message_id=None):
     method_url = 'unpinChatMessage'
     payload = {'chat_id': chat_id, 'message_id': message_id}
     return _make_request(token, method_url, params=payload, method='post')