diff --git a/backend/schedule/models.py b/backend/schedule/models.py
index 9e1716be26..b6326d76f7 100644
--- a/backend/schedule/models.py
+++ b/backend/schedule/models.py
@@ -347,7 +347,7 @@ def speakers(self):
         speakers.extend(
             [speaker.user for speaker in self.additional_speakers.order_by("id").all()]
         )
-        return speakers
+        return [speaker for speaker in speakers if speaker is not None]
 
     def clean(self):
         if self.type == ScheduleItem.TYPES.submission and not self.submission: