diff --git a/package.json b/package.json
index a9f14112c..bbea73e8b 100644
--- a/package.json
+++ b/package.json
@@ -1,5 +1,5 @@
 {
-  "version": "39.1.0",
+  "version": "39.1.1",
   "license": "MIT",
   "sideEffects": false,
   "main": "dist/cjs/index.js",
diff --git a/src/client.ts b/src/client.ts
index 72a52deac..388776c89 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -68,7 +68,7 @@ import {
 import { HttpClient } from './clientAdapter';
 
 /** Current SDK version */
-export const SDK_VERSION = '39.1.0';
+export const SDK_VERSION = '39.1.1';
 export class Client implements ClientInterface {
   private _config: Readonly<Configuration>;
   private _timeout: number;
@@ -140,7 +140,7 @@ export class Client implements ClientInterface {
     };
 
     this._userAgent = updateUserAgent(
-      'Square-TypeScript-SDK/39.1.0 ({api-version}) {engine}/{engine-version} ({os-info}) {detail}',
+      'Square-TypeScript-SDK/39.1.1 ({api-version}) {engine}/{engine-version} ({os-info}) {detail}',
       this._config.squareVersion,
       this._config.userAgentDetail
     );
diff --git a/src/models/refund.ts b/src/models/refund.ts
index 25d5562fa..8dd2bd1ee 100644
--- a/src/models/refund.ts
+++ b/src/models/refund.ts
@@ -22,7 +22,7 @@ export interface Refund {
   /** The ID of the transaction that the refunded tender is part of. */
   transactionId?: string | null;
   /** The ID of the refunded tender. */
-  tenderId: string;
+  tenderId?: string;
   /** The timestamp for when the refund was created, in RFC 3339 format. */
   createdAt?: string;
   /** The reason for the refund being issued. */
@@ -58,7 +58,7 @@ export const refundSchema: Schema<Refund> = object({
   id: ['id', string()],
   locationId: ['location_id', string()],
   transactionId: ['transaction_id', optional(nullable(string()))],
-  tenderId: ['tender_id', string()],
+  tenderId: ['tender_id', optional(string())],
   createdAt: ['created_at', optional(string())],
   reason: ['reason', string()],
   amountMoney: ['amount_money', lazy(() => moneySchema)],