diff --git a/migrations/010_add_soft_delete.sql b/migrations/010_add_soft_delete.sql
index 74b8588..12162b4 100644
--- a/migrations/010_add_soft_delete.sql
+++ b/migrations/010_add_soft_delete.sql
@@ -6,4 +6,5 @@ ALTER TABLE people ADD COLUMN deleted_at TEXT;
 ALTER TABLE stations ADD COLUMN deleted_at TEXT;
 ALTER TABLE work_records ADD COLUMN deleted_at TEXT;
 ALTER TABLE work_records ADD COLUMN attachments TEXT;
-ALTER TABLE work_records ADD COLUMN created_at TEXT NOT NULL DEFAULT (datetime('now', 'localtime'));
+ALTER TABLE work_records ADD COLUMN created_at TEXT;
+UPDATE work_records SET created_at = datetime('now', 'localtime') WHERE created_at IS NULL;