diff --git a/seminar/migrations/0095_fix_polymorphism.py b/seminar/migrations/0095_fix_polymorphism.py
new file mode 100644
index 00000000..cba9bda1
--- /dev/null
+++ b/seminar/migrations/0095_fix_polymorphism.py
@@ -0,0 +1,25 @@
+# Generated by Django 2.2.17 on 2021-07-01 00:44
+
+from django.db import migrations
+
+def fix_all(apps, schema_editor):
+	ContentType = apps.get_model('contenttypes', 'ContentType')
+	for modelname in [
+			# Problémy:
+			'Konfera', 'Tema', 'Uloha', 'Clanek'
+			# TreeNody:
+			'RocnikNode', 'CisloNode', 'MezicisloNode', 'TemaVCisleNode', 'OrgTextNode', 'UlohaZadaniNode', 'PohadkaNode', 'UlohaVzorakNode', 'TextNode', 'CastNode', 'ReseniNode'
+			]:
+		Model = apps.get_model('seminar', modelname)
+		ct = ContentType.objects.get_for_model(Model)
+		Model.objects.update(polymorphic_ctype_id=ct)
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('seminar', '0094_auto_20210701_0149'),
+    ]
+
+    operations = [
+        migrations.RunPython(fix_all, migrations.RunPython.noop),
+    ]