diff --git a/redditbot.py b/redditbot.py
index f0d9e04..8e0565d 100644
--- a/redditbot.py
+++ b/redditbot.py
@@ -207,7 +207,11 @@ async def main():
                         j = j[0]
                         k = k[0]
                 attributes = []
-                mimetype = (await _get_file_mimetype(k)) if k else ''
+                try:
+                    mimetype = (await _get_file_mimetype(k)) if k else ''
+                except TypeError:
+                    # (for now) telethon doesn't easily support attributes for grouped media
+                    mimetype = ''
                 if mimetype.startswith('video/'):
                     try:
                         data = await _get_video_data(k)