diff --git a/stude/student_status/serializers.py b/stude/student_status/serializers.py
index 6276c15..f0def37 100644
--- a/stude/student_status/serializers.py
+++ b/stude/student_status/serializers.py
@@ -68,7 +68,7 @@ class StudentStatusSerializer(serializers.ModelSerializer):
                 old_study_group.delete()
 
         # If student has changed study group, check if the old study_group no longer has any students
-        if study_group is not old_study_group and old_study_group is not None:
+        if study_group is not None and study_group is not old_study_group and old_study_group is not None:
             if not old_study_group.students.exists():
                 # If there are no students left in the old StudyGroup, delete it
                 old_study_group.delete()