diff --git a/demos/er.html b/demos/er.html
index 0f376bf9e..5bccb212e 100644
--- a/demos/er.html
+++ b/demos/er.html
@@ -23,7 +23,7 @@ ORDER ||--|{ LINE-ITEM : contains
 CUSTOMER }|..|{ DELIVERY-ADDRESS : uses
     </pre>
 
-    <script src="./mermaid.js"></script>
+    <script src="./mermaid.esm.mjs" type="module"></script>
     <script>
       mermaid.initialize({
         theme: 'forest',