diff --git a/bookwyrm/tests/validate_html.py b/bookwyrm/tests/validate_html.py
index 423a86586..85e5c6277 100644
--- a/bookwyrm/tests/validate_html.py
+++ b/bookwyrm/tests/validate_html.py
@@ -8,6 +8,7 @@ def validate_html(html):
     _, errors = tidy_document(
         html.content,
         options={
+            "doctype": "html5",
             "drop-empty-elements": False,
             "warn-proprietary-attributes": False,
         },