diff --git a/src/pretix/base/exporters/invoices.py b/src/pretix/base/exporters/invoices.py
index 62a37dcad4..dbaa14d416 100644
--- a/src/pretix/base/exporters/invoices.py
+++ b/src/pretix/base/exporters/invoices.py
@@ -6,6 +6,7 @@ from django.dispatch import receiver
 from django.utils.translation import ugettext as _
 
 from ..exporter import BaseExporter
+from ..services.invoices import invoice_pdf_task
 from ..signals import register_data_exporters
 
 
@@ -17,6 +18,9 @@ class InvoiceExporter(BaseExporter):
         with tempfile.TemporaryDirectory() as d:
             with ZipFile(os.path.join(d, 'tmp.zip'), 'w') as zipf:
                 for i in self.event.invoices.all():
+                    if not i.file:
+                        invoice_pdf_task.apply_async(args=(i.pk))
+                        i.refresh_from_db()
                     i.file.open('r')
                     zipf.writestr('{}.pdf'.format(i.number), i.file.read())
                     i.file.close()
diff --git a/src/pretix/helpers/profile/middleware.py b/src/pretix/helpers/profile/middleware.py
index 312aa57d04..1084773287 100644
--- a/src/pretix/helpers/profile/middleware.py
+++ b/src/pretix/helpers/profile/middleware.py
@@ -1,8 +1,8 @@
 import cProfile
 import os
 import random
-
 import time
+
 from django.conf import settings
 
 
diff --git a/src/pretix/plugins/sendmail/views.py b/src/pretix/plugins/sendmail/views.py
index e19f5a522f..fce9d76394 100644
--- a/src/pretix/plugins/sendmail/views.py
+++ b/src/pretix/plugins/sendmail/views.py
@@ -1,7 +1,7 @@
 import logging
 from datetime import timedelta
-import pytz
 
+import pytz
 from django.contrib import messages
 from django.db.models import Q
 from django.shortcuts import redirect