diff --git a/telethon/telegram_client.py b/telethon/telegram_client.py
index 0c8cfc64..76141425 100644
--- a/telethon/telegram_client.py
+++ b/telethon/telegram_client.py
@@ -286,8 +286,10 @@ class TelegramClient(TelegramBareClient):
             )
             offset_id = r.messages[-1].id & 4294967296  # Telegram/danog magic
 
-        # Sort by message date
-        no_date = datetime.fromtimestamp(0)
+        # Sort by message date. Windows will raise if timestamp is 0,
+        # so we need to set at least one day ahead while still being
+        # the smallest date possible.
+        no_date = datetime.fromtimestamp(86400)
         ds = sorted(
             list(dialogs.values()),
             key=lambda d: getattr(messages[d.top_message], 'date', no_date)
@@ -941,8 +943,8 @@ class TelegramClient(TelegramBareClient):
            If even after
         """
         if isinstance(peer, str):
-            # Let .get_entity resolve the username or phone
-            return utils.get_input_peer(self.get_entity(peer))
+            # Let .get_entity resolve the username or phone (full entity)
+            peer = self.get_entity(peer)
 
         is_peer = False
         if isinstance(peer, int):
@@ -950,9 +952,12 @@ class TelegramClient(TelegramBareClient):
             is_peer = True
 
         elif isinstance(peer, TLObject):
-            if type(peer).SUBCLASS_OF_ID == 0xc91c90b6:  # crc32(b'InputPeer')
-                return peer
             is_peer = type(peer).SUBCLASS_OF_ID == 0x2d45687  # crc32(b'Peer')
+            if not is_peer:
+                try:
+                    return utils.get_input_peer(peer)
+                except ValueError:
+                    pass
 
         if not is_peer:
             raise ValueError(