diff --git a/src/pretix/base/models/vouchers.py b/src/pretix/base/models/vouchers.py
index 52ddf138c8..cd6c4bafac 100644
--- a/src/pretix/base/models/vouchers.py
+++ b/src/pretix/base/models/vouchers.py
@@ -460,7 +460,7 @@ class Voucher(LoggedModel):
             new_quotas = set(
                 Quota.objects.filter(
                     pk__in=Quota.variations.through.objects.filter(
-                        itemvariation__item=old_instance.item,
+                        itemvariation__item=item,
                         quota__subevent=data.get('subevent'),
                     ).values('quota_id')
                 )
diff --git a/src/pretix/control/forms/vouchers.py b/src/pretix/control/forms/vouchers.py
index 96866bb41b..98630dcf51 100644
--- a/src/pretix/control/forms/vouchers.py
+++ b/src/pretix/control/forms/vouchers.py
@@ -90,8 +90,10 @@ class VoucherForm(I18nModelForm):
     def __init__(self, *args, **kwargs):
         instance = kwargs.get('instance')
         initial = kwargs.get('initial')
+        self.initial_instance_data = None
         if instance:
-            self.initial_instance_data = modelcopy(instance)
+            if instance.pk:
+                self.initial_instance_data = modelcopy(instance)
             try:
                 if instance.variation:
                     initial['itemvar'] = '%d-%d' % (instance.item.pk, instance.variation.pk)
@@ -101,8 +103,6 @@ class VoucherForm(I18nModelForm):
                     initial['itemvar'] = 'q-%d' % instance.quota.pk
             except Item.DoesNotExist:
                 pass
-        else:
-            self.initial_instance_data = None
         super().__init__(*args, **kwargs)
 
         if instance.event.has_subevents:
@@ -234,8 +234,8 @@ class VoucherForm(I18nModelForm):
         )
         if check_quota:
             Voucher.clean_quota_check(
-                data, cnt, self.initial_instance_data, self.instance.event,
-                self.instance.quota, self.instance.item, self.instance.variation
+                data, cnt, self.initial_instance_data,
+                self.instance.event, self.instance.quota, self.instance.item, self.instance.variation
             )
         Voucher.clean_voucher_code(data, self.instance.event, self.instance.pk)
         if 'seat' in self.fields and data.get('seat'):