diff --git a/src/pretix/base/services/cross_selling.py b/src/pretix/base/services/cross_selling.py
index e3f13068fe..bf9ce80fdd 100644
--- a/src/pretix/base/services/cross_selling.py
+++ b/src/pretix/base/services/cross_selling.py
@@ -65,7 +65,7 @@ class CrossSellingService:
             result = (
                 (category,
                  self._prepare_items(None, items_qs, discount_info),
-                 None)
+                 '')
                 for (category, items_qs, discount_info) in self._applicable_categories(0)
             )
         return [(category, items, form_prefix) for (category, items, form_prefix) in result if len(items) > 0]
diff --git a/src/pretix/presale/checkoutflow.py b/src/pretix/presale/checkoutflow.py
index 4fafeaa39a..781c4167f1 100644
--- a/src/pretix/presale/checkoutflow.py
+++ b/src/pretix/presale/checkoutflow.py
@@ -631,7 +631,7 @@ class AddOnsStep(CartMixin, AsyncAction, TemplateFlowStep):
 
     @cached_property
     def cross_selling_is_applicable(self):
-        return any(len(items) > 0 for (category, items) in self.cross_selling_data)
+        return any(len(items) > 0 for (category, items, form_prefix) in self.cross_selling_data)
 
     @cached_property
     def cross_selling_data(self):