diff --git a/cap-notebook/demoapp/srv/attachment-extension.cds b/cap-notebook/demoapp/srv/attachment-extension.cds
index efca2f8f..732ac6b1 100644
--- a/cap-notebook/demoapp/srv/attachment-extension.cds
+++ b/cap-notebook/demoapp/srv/attachment-extension.cds
@@ -50,6 +50,7 @@ annotate Books.attachments with {
 
 
 annotate Books.references with {
+  content @Validation.Maximum : '100MB';
   status @(
     Common.Text: {
       $value: ![statusText.text],