[#8445] added constrain on MarkupSafe
diff --git a/requirements.in b/requirements.in
index 1546be7..4bfbabc 100644
--- a/requirements.in
+++ b/requirements.in
@@ -16,7 +16,7 @@
 Jinja2
 Markdown
 markdown-checklist
-MarkupSafe
+MarkupSafe!=2.1.1
 Ming
 # TODO: move to "oauthlib" instead
 # oauth2 doesn't have a release with py3.6 support, but does have fixes on master: