diff --git a/src/core/models/schedules.py b/src/core/models/schedules.py
index aed616a497c2659faa6e4b1bf292f6dd723c06bc..647c0b419e38cc3d2e46491e270445347e1957f2 100644
--- a/src/core/models/schedules.py
+++ b/src/core/models/schedules.py
@@ -427,7 +427,7 @@ class ScheduleSource(models.Model):
         allow_track = cfg.get('import_tracks') or False
 
         # note down all existing rooms, events and speakers so that we can call out the missing ones
-        if self.assembly:
+        if self.assembly and cfg.get('missing_rooms') != 'ignore':
             expected_rooms = list(self.assembly.rooms.values_list('id', flat=True))
         else:
             expected_rooms = list(