diff --git a/synapse/rest/media/v1/preview_html.py b/synapse/rest/media/v1/preview_html.py
index afe4e2975..516d0434f 100644
--- a/synapse/rest/media/v1/preview_html.py
+++ b/synapse/rest/media/v1/preview_html.py
@@ -20,7 +20,8 @@ from typing import (
     Dict,
     Generator,
     Iterable,
-   List, Optional,
+    List,
+    Optional,
     Set,
     Union,
 )