diff --git a/app/assets/javascripts/discourse/app/components/header.gjs b/app/assets/javascripts/discourse/app/components/header.gjs
index 95572a67798..0b459b57074 100644
--- a/app/assets/javascripts/discourse/app/components/header.gjs
+++ b/app/assets/javascripts/discourse/app/components/header.gjs
@@ -222,7 +222,7 @@ export default class GlimmerHeader extends Component {
       </div>
       <PluginOutlet
         @name="after-header"
-        @outletArgs={{hash minimized=(Boolean this.header.topic)}}
+        @outletArgs={{hash minimized=(globalThis.Boolean this.header.topic)}}
       />
     </header>
   </template>