diff --git a/telethon/tl/custom/message.py b/telethon/tl/custom/message.py
index df965b52..7ebc00a5 100644
--- a/telethon/tl/custom/message.py
+++ b/telethon/tl/custom/message.py
@@ -185,6 +185,10 @@ class Message(ChatGetter, SenderGetter, TLObject, abc.ABC):
         else:
             self._chat_peer = to_id
 
+        if post and not from_id and self._chat_peer:
+            # If the message comes from a Channel, let the sender be it
+            self._sender_id = utils.get_peer_id(self._chat_peer)
+
         self._broadcast = post
         self._chat = None
         self._input_chat = None
diff --git a/telethon/tl/custom/sendergetter.py b/telethon/tl/custom/sendergetter.py
index a0359550..0f70d3f2 100644
--- a/telethon/tl/custom/sendergetter.py
+++ b/telethon/tl/custom/sendergetter.py
@@ -14,8 +14,8 @@ class SenderGetter(abc.ABC):
     @property
     def sender(self):
         """
-        Returns the :tl:`User` that created this object. It may be ``None``
-        if the object has no sender or if Telegram didn't send the sender.
+        Returns the :tl:`User` or :tl:`Channel` that sent this object.
+        It may be ``None`` if Telegram didn't send the sender.
 
         If you're using `telethon.events`, use `get_sender` instead.
         """
@@ -37,7 +37,7 @@ class SenderGetter(abc.ABC):
     @property
     def input_sender(self):
         """
-        This :tl:`InputPeer` is the input version of the user who
+        This :tl:`InputPeer` is the input version of the user/channel who
         sent the message. Similarly to `input_chat`, this doesn't have
         things like username or similar, but still useful in some cases.