diff --git a/state/migrations/20230822174049_bogus_snapshot_cleanup.sql b/state/migrations/20230822174049_bogus_snapshot_cleanup.sql
new file mode 100644
index 00000000..063bc1ae
--- /dev/null
+++ b/state/migrations/20230822174049_bogus_snapshot_cleanup.sql
@@ -0,0 +1,32 @@
+-- +goose Up
+-- This migration runs a one-time cleanup job to delete rooms with dodgy state snapshots.
+-- A room is dodgy if its current snapshot lacks a create event.
+BEGIN;
+
+CREATE TEMPORARY TABLE bogus_rooms AS (
+    SELECT room_id, current_snapshot_id
+    FROM syncv3_rooms
+    WHERE room_id NOT IN (
+        SELECT room_id
+        FROM syncv3_events
+        WHERE event_type = 'm.room.create'
+          AND state_key = ''
+    )
+);
+
+DELETE
+FROM syncv3_events
+WHERE room_id IN (SELECT room_id FROM bogus_rooms);
+
+DELETE
+FROM syncv3_snapshots
+WHERE room_id IN (SELECT room_id FROM bogus_rooms);
+
+DELETE
+FROM syncv3_rooms
+WHERE room_id IN (SELECT room_id FROM bogus_rooms);
+
+COMMIT;
+
+-- +goose Down
+-- downgrading is a no-op.