diff --git a/app/extensions/polls/page.mdx b/app/extensions/polls/page.mdx
index a32f3ea..dc048d2 100644
--- a/app/extensions/polls/page.mdx
+++ b/app/extensions/polls/page.mdx
@@ -29,7 +29,7 @@ Note that there is no `question` field: the question should be included in the `
             <Property name="multiple_choice" type="boolean" required="true">
                 Whether the poll allows multiple votes to be cast for different options.
             </Property>
-            <Property name="expires_at" type="ISO 8601" typeLink="/types#iso8601" required="false">
+            <Property name="expires_at" type="ISO 8601" typeLink="/types#iso8601">
                 ISO 8601 timestamp of when the poll ends and no more votes can be cast. If not present, the poll does not expire.
             </Property>
         </Properties>