diff --git a/telethon/client/downloads.py b/telethon/client/downloads.py
index c5a00358..67388e44 100644
--- a/telethon/client/downloads.py
+++ b/telethon/client/downloads.py
@@ -439,7 +439,8 @@ class DownloadMethods:
                     if inspect.isawaitable(r):
                         await r
 
-            if hasattr(f, 'flush') and callable(getattr(f, 'flush')):
+            # Not all IO objects have flush (see #1227)
+            if callable(getattr(f, 'flush', None)):
                 f.flush()
 
             if in_memory: