diff --git a/snippets/mint_system.account.report_invoice_document.add_header_text.xml b/snippets/mint_system.account.report_invoice_document.add_header_text.xml
index 433c65c2..a24ad017 100644
--- a/snippets/mint_system.account.report_invoice_document.add_header_text.xml
+++ b/snippets/mint_system.account.report_invoice_document.add_header_text.xml
@@ -1,6 +1,10 @@
 <data inherit_id="account.report_invoice_document" priority="50">
     <xpath expr="//table[@name='invoice_line_table']" position="before">
-       Gemäss Rahmen-Dienstleistungsvertrag <span t-esc="', '.join(o.invoice_line_ids.sale_line_ids.order_id.mapped('x_blanket_order'))"/>
+    <t t-if="', '.join([str(x) for x in o.invoice_line_ids.sale_line_ids.order_id.mapped('x_blanket_order') if x])" >
+            
+        Gemäss Rahmen-Dienstleistungsvertrag <span t-esc="', '.join([str(x) for x in o.invoice_line_ids.sale_line_ids.order_id.mapped('x_blanket_order') if x])" />
  erlauben wir uns, für unsere augeführten IPR-Leistungen folgende Rechnung zu stellen:
+
+        </t>
     </xpath>
 </data>
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