diff --git a/src/pretix/api/views/event.py b/src/pretix/api/views/event.py
index 63cc853309..114fdf38c4 100644
--- a/src/pretix/api/views/event.py
+++ b/src/pretix/api/views/event.py
@@ -73,6 +73,7 @@ class EventViewSet(viewsets.ModelViewSet):
     queryset = Event.objects.none()
     lookup_field = 'slug'
     lookup_url_kwarg = 'event'
+    lookup_value_regex = '[^/]+'
     permission_classes = (EventCRUDPermission,)
     filter_backends = (DjangoFilterBackend, filters.OrderingFilter)
     ordering = ('slug',)
diff --git a/src/pretix/api/views/organizer.py b/src/pretix/api/views/organizer.py
index bf93b1961d..1c5d79df2b 100644
--- a/src/pretix/api/views/organizer.py
+++ b/src/pretix/api/views/organizer.py
@@ -29,6 +29,7 @@ class OrganizerViewSet(viewsets.ReadOnlyModelViewSet):
     queryset = Organizer.objects.none()
     lookup_field = 'slug'
     lookup_url_kwarg = 'organizer'
+    lookup_value_regex = '[^/]+'
     filter_backends = (filters.OrderingFilter,)
     ordering = ('slug',)
     ordering_fields = ('name', 'slug')