diff --git a/polylan_submitter/submissions/migrations/0009_repair_legacy_tables.py b/polylan_submitter/submissions/migrations/0009_repair_legacy_tables.py
new file mode 100644
index 0000000..227496d
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+++ b/polylan_submitter/submissions/migrations/0009_repair_legacy_tables.py
@@ -0,0 +1,58 @@
+from django.db import migrations
+
+
+# Before the submissions -> opus_magnum rename, this app owned the opus magnum
+# tables and its 0001_initial was already applied. The new 0001_initial has the
+# same name, so on those databases Django skipped it and kept the legacy
+# submissions_submission / submissions_submissionfile layout (is_validated NOT
+# NULL, response_id, ...) and never created submissions_imagecrop.
+LEGACY_TABLES = [
+    "submissions_imagecrop",
+    "submissions_submissionfile",
+    "submissions_puzzleresponse",
+    "submissions_submission",
+    "submissions_steamcollectionitem",
+    "submissions_steamcollection",
+    "submissions_steamapikey",
+]
+
+
+def repair_legacy_tables(apps, schema_editor):
+    connection = schema_editor.connection
+
+    with connection.cursor() as cursor:
+        columns = {
+            col.name
+            for col in connection.introspection.get_table_description(
+                cursor, "submissions_submission"
+            )
+        }
+
+        if "is_validated" not in columns:
+            return
+
+        # Data was copied to opus_magnum (0015) and 0007 wiped submissions, so
+        # this should be empty: refuse to drop anything otherwise.
+        cursor.execute("SELECT COUNT(*) FROM submissions_submission")
+        if cursor.fetchone()[0]:
+            raise RuntimeError(
+                "submissions_submission has the legacy layout but is not empty"
+            )
+
+    existing_tables = set(connection.introspection.table_names())
+    for table in LEGACY_TABLES:
+        if table in existing_tables:
+            schema_editor.execute(f"DROP TABLE {schema_editor.quote_name(table)}")
+
+    for model_name in ["Submission", "SubmissionFile", "ImageCrop"]:
+        schema_editor.create_model(apps.get_model("submissions", model_name))
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("submissions", "0008_remove_submission_game"),
+    ]
+
+    operations = [
+        migrations.RunPython(repair_legacy_tables, migrations.RunPython.noop),
+    ]