diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index 38ace40b..81deae64 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -749,14 +749,17 @@ class _ContainerQueue(asyncio.Queue):
                 isinstance(result.obj, MessageContainer):
             return result
 
+        size = result.size()
         result = [result]
         while not self.empty():
             item = self.get_nowait()
-            if item == _reconnect_sentinel or\
-                    isinstance(item.obj, MessageContainer):
+            if (item == _reconnect_sentinel or
+                isinstance(item.obj, MessageContainer)
+                    or size + item.size() > MessageContainer.MAXIMUM_SIZE):
                 self.put_nowait(item)
                 break
             else:
+                size += item.size()
                 result.append(item)
 
         return result
diff --git a/telethon/tl/core/messagecontainer.py b/telethon/tl/core/messagecontainer.py
index f5c3c378..fc36fd5e 100644
--- a/telethon/tl/core/messagecontainer.py
+++ b/telethon/tl/core/messagecontainer.py
@@ -10,6 +10,11 @@ __log__ = logging.getLogger(__name__)
 class MessageContainer(TLObject):
     CONSTRUCTOR_ID = 0x73f1f8dc
 
+    # Maximum size in bytes for the inner payload of the container.
+    # Telegram will close the connection if the payload is bigger.
+    # The overhead of the container itself is subtracted.
+    MAXIMUM_SIZE = 1044456 - 8
+
     def __init__(self, messages):
         self.messages = messages
 
diff --git a/telethon/tl/core/tlmessage.py b/telethon/tl/core/tlmessage.py
index d0345cb2..5d032c7c 100644
--- a/telethon/tl/core/tlmessage.py
+++ b/telethon/tl/core/tlmessage.py
@@ -82,3 +82,6 @@ class TLMessage(TLObject):
             raise TypeError('Incoming messages should not be bytes()-ed')
 
         return self._body
+
+    def size(self):
+        return len(self._body)