diff --git a/framework/core/js/src/forum/components/Post.js b/framework/core/js/src/forum/components/Post.js
index 5fd0c8e5f..df13321ec 100644
--- a/framework/core/js/src/forum/components/Post.js
+++ b/framework/core/js/src/forum/components/Post.js
@@ -138,7 +138,7 @@ export default class Post extends Component {
       classes.push('Post--by-actor');
     }
 
-    if (user?.id() === discussion.attribute('startUserId')) {
+    if (user && user?.id() === discussion.attribute('startUserId')) {
       classes.push('Post--by-start-user');
     }