diff --git a/src/pretix/base/services/orders.py b/src/pretix/base/services/orders.py
index 1a28aeec1f..e67a4ea2cb 100644
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -199,7 +199,7 @@ def approve_order(order, user=None, send_mail: bool=True, auth=None):
     invoice = order.invoices.last()  # Might be generated by plugin already
     if order.event.settings.get('invoice_generate') == 'True' and invoice_qualified(order):
         if not invoice:
-            generate_invoice(
+            invoice = generate_invoice(
                 order,
                 trigger_pdf=not order.event.settings.invoice_email_attachment or not order.email
             )