diff --git a/stubs/ujson/METADATA.toml b/stubs/ujson/METADATA.toml
index b0b13fe94..6f9cb91f0 100644
--- a/stubs/ujson/METADATA.toml
+++ b/stubs/ujson/METADATA.toml
@@ -1,2 +1,3 @@
 version = "5.10.*"
 upstream_repository = "https://github.com/ultrajson/ultrajson"
+obsolete_since = "5.11.0" # Released on 2025-08-20