diff --git a/ox/torrent/bencode3.py b/ox/torrent/bencode3.py
index 0b7788e..eefda6f 100644
--- a/ox/torrent/bencode3.py
+++ b/ox/torrent/bencode3.py
@@ -121,7 +121,7 @@ def _encode_dict(d, buff):
     """
     buff.append(b'd')
     for k in sorted(d):
-        if not isinstance(k, [bytes, str]):
+        if not isinstance(k, (bytes, str)):
             k = str(k)
         _encode(k, buff)
         _encode(d[k], buff)