diff --git a/aleksis/apps/untis/migrations/0003_guess_school_id.py b/aleksis/apps/untis/migrations/0003_guess_school_id.py
index 090fd6d96071dbbd5170bf0ac757040be1048f01..a41213476598c8260565ca12b1f703414508ff27 100644
--- a/aleksis/apps/untis/migrations/0003_guess_school_id.py
+++ b/aleksis/apps/untis/migrations/0003_guess_school_id.py
@@ -16,7 +16,7 @@ def guess_school_id(apps, schema_editor):
     if not vr or not vr.school_id_untis:
         return
 
-    get_site_preferences()["untis_mysql__school_id"] = school_id
+    get_site_preferences()["untis_mysql__school_id"] = vr.school_id_untis
 
 
 class Migration(migrations.Migration):