diff --git a/src/pretix/control/views/orders.py b/src/pretix/control/views/orders.py
index 95bc3a5e5..f6f9b2fc3 100644
--- a/src/pretix/control/views/orders.py
+++ b/src/pretix/control/views/orders.py
@@ -499,7 +499,7 @@ class OrderChange(OrderView):
                 try:
                     ocm.add_position(item, variation,
                                      self.add_form.cleaned_data['price'],
-                                     self.add_form.cleaned_data['addon_to'])
+                                     self.add_form.cleaned_data.get('addon_to'))
                 except OrderError as e:
                     self.add_form.custom_error = str(e)
                     return False
diff --git a/src/tests/control/test_orders.py b/src/tests/control/test_orders.py
index 065afb0e7..89b196647 100644
--- a/src/tests/control/test_orders.py
+++ b/src/tests/control/test_orders.py
@@ -487,6 +487,7 @@ class OrderChangeTests(SoupTest):
             'op-{}-itemvar'.format(self.op1.pk): str(self.shirt.pk),
             'op-{}-operation'.format(self.op2.pk): '',
             'op-{}-itemvar'.format(self.op2.pk): str(self.ticket.pk),
+            'add-itemvar'.format(self.op2.pk): str(self.ticket.pk),
         })
         self.op1.refresh_from_db()
         self.order.refresh_from_db()
@@ -504,6 +505,7 @@ class OrderChangeTests(SoupTest):
             'op-{}-price'.format(self.op1.pk): '24.00',
             'op-{}-operation'.format(self.op2.pk): '',
             'op-{}-itemvar'.format(self.op2.pk): str(self.ticket.pk),
+            'add-itemvar'.format(self.op2.pk): str(self.ticket.pk),
         })
         self.op1.refresh_from_db()
         self.order.refresh_from_db()
@@ -521,6 +523,7 @@ class OrderChangeTests(SoupTest):
             'op-{}-operation'.format(self.op2.pk): '',
             'op-{}-itemvar'.format(self.op2.pk): str(self.ticket.pk),
             'op-{}-price'.format(self.op2.pk): str(self.op2.price),
+            'add-itemvar'.format(self.op2.pk): str(self.ticket.pk),
         })
         self.order.refresh_from_db()
         assert self.order.positions.count() == 1