diff --git a/seminar/migrations/0002_treenode_polymorphic_ctype.py b/seminar/migrations/0002_treenode_polymorphic_ctype.py
new file mode 100644
index 00000000..4398be6c
--- /dev/null
+++ b/seminar/migrations/0002_treenode_polymorphic_ctype.py
@@ -0,0 +1,20 @@
+# Generated by Django 2.2.4 on 2019-08-13 19:36
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contenttypes', '0002_remove_content_type_name'),
+        ('seminar', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='treenode',
+            name='polymorphic_ctype',
+            field=models.ForeignKey(editable=False, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='polymorphic_seminar.treenode_set+', to='contenttypes.ContentType'),
+        ),
+    ]
diff --git a/seminar/migrations/0003_problem_polymorphic_ctype.py b/seminar/migrations/0003_problem_polymorphic_ctype.py
new file mode 100644
index 00000000..279efbf4
--- /dev/null
+++ b/seminar/migrations/0003_problem_polymorphic_ctype.py
@@ -0,0 +1,20 @@
+# Generated by Django 2.2.4 on 2019-08-13 19:45
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contenttypes', '0002_remove_content_type_name'),
+        ('seminar', '0002_treenode_polymorphic_ctype'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='problem',
+            name='polymorphic_ctype',
+            field=models.ForeignKey(editable=False, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='polymorphic_seminar.problem_set+', to='contenttypes.ContentType'),
+        ),
+    ]
diff --git a/seminar/models.py b/seminar/models.py
index cab97533..6efd27dd 100644
--- a/seminar/models.py
+++ b/seminar/models.py
@@ -584,7 +584,8 @@ class Soustredeni(SeminarModelBase):
 
 
 @reversion.register(ignore_duplicates=True)
-class Problem(SeminarModelBase):
+# Pozor na následující řádek. *Nekrmit, asi kouše!*
+class Problem(SeminarModelBase,PolymorphicModel):
 
 	class Meta:
 		# Není abstraktní, protože se na něj jinak nedají dělat ForeignKeys.