diff --git a/keystone/trust/schema.py b/keystone/trust/schema.py
index 20c85b3907..47174b7b97 100644
--- a/keystone/trust/schema.py
+++ b/keystone/trust/schema.py
@@ -151,7 +151,7 @@
         "roles_links": response_types.links,
         **_trust_properties,
     },
-    "additionalProperties": False,
+    "additionalProperties": True,
 }
 
 trust_index_request_query: dict[str, Any] = {