diff --git a/src/controllers/05-payment-controller.ts b/src/controllers/05-payment-controller.ts
index 7856f1c..8ac6b62 100644
--- a/src/controllers/05-payment-controller.ts
+++ b/src/controllers/05-payment-controller.ts
@@ -333,7 +333,7 @@ export class FlowAccountController extends Controller {
 
       await prisma.invoice.update({
         where: { id: payment.invoice.id },
-        data: { flowAccountRecordId: documentId },
+        data: { flowAccountRecordId: String(documentId) },
       });
 
       if (documentId) {