diff --git a/elements/design-host/design-host.html b/elements/design-host/design-host.html
index c562f158..9ceea51e 100644
--- a/elements/design-host/design-host.html
+++ b/elements/design-host/design-host.html
@@ -7,6 +7,7 @@
 Polymer({
 
   name: 'my-element',
+  __designHost: true,
 
   ready: function() {
     this.model = {};