diff --git a/aggregator/models.py b/aggregator/models.py
index 831cfb4..9558917 100644
--- a/aggregator/models.py
+++ b/aggregator/models.py
@@ -11,14 +11,14 @@ from pyrogram import Chat as PyrogramChat, Message as PyrogramMessage
 class AggregationSource(models.Model):
     owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
     title = models.CharField(max_length=64)
-    chat_id = models.CharField(db_index=True, max_length=64)
+    chat_id = models.BigIntegerField(db_index=True)
 
     def __str__(self):
         return self.title
 
 
 class Chat(models.Model):
-    chat_id = models.CharField(db_index=True, max_length=64)
+    chat_id = models.BigIntegerField(db_index=True)
     title = models.TextField()
     username = models.CharField(max_length=64, null=True, blank=True)
     photo = models.ImageField(null=True, blank=True)