diff --git a/website/templates/playground.html b/website/templates/playground.html
index a104363..28e9ba4 100644
--- a/website/templates/playground.html
+++ b/website/templates/playground.html
@@ -13,16 +13,16 @@
             <textarea id="mlf-editor" spellcheck="false">/// A forum thread
 record thread {
     /// Thread title
-    title: string constrained {
+    title!: string constrained {
         maxLength: 200,
         minLength: 1,
     },
     /// Thread body
-    body?: string constrained {
+    body: string constrained {
         maxLength: 10000,
     },
     /// Thread creation timestamp
-    createdAt: Datetime,
+    createdAt!: Datetime,
 }</textarea>
         </div>