diff --git a/README.md b/README.md
index 1efbe0b..e9e21f6 100644
--- a/README.md
+++ b/README.md
@@ -125,12 +125,12 @@ const encodedKey = readFile(filePath) // Specific implementation may vary
 
 const productId = "<product_id>"
 const subscriptionOfferId = "<subscription_offer_id>"
-const applicationUsername = "<application_username>"
+const appAccountToken = "<app_account_token>"
 const nonce = "<nonce>"
 const timestamp = Date.now()
 const signatureCreator = new PromotionalOfferSignatureCreator(encodedKey, keyId, bundleId)
 
-const signature = signatureCreator.createSignature(productId, subscriptionOfferId, applicationUsername, nonce, timestamp)
+const signature = signatureCreator.createSignature(productId, subscriptionOfferId, appAccountToken, nonce, timestamp)
 console.log(signature)
 ```
 
diff --git a/promotional_offer.ts b/promotional_offer.ts
index 94e32aa..cf1c4c0 100644
--- a/promotional_offer.ts
+++ b/promotional_offer.ts
@@ -20,17 +20,17 @@ export class PromotionalOfferSignatureCreator {
      * {@link https://developer.apple.com/documentation/storekit/in-app_purchase/original_api_for_in-app_purchase/subscriptions_and_offers/generating_a_signature_for_promotional_offers Generating a signature for promotional offers}
      * @param productIdentifier The subscription product identifier
      * @param subscriptionOfferID The subscription discount identifier
-     * @param applicationUsername An optional string value that you define; may be an empty string
+     * @param appAccountToken An optional string value that you define; may be an empty string
      * @param nonce A one-time UUID value that your server generates. Generate a new nonce for every signature.
      * @param timestamp A timestamp your server generates in UNIX time format, in milliseconds. The timestamp keeps the offer active for 24 hours.
      * @return The Base64 encoded signature
      */
-    public createSignature(productIdentifier: string, subscriptionOfferID: string, applicationUsername: string, nonce: string, timestamp: number): string {
+    public createSignature(productIdentifier: string, subscriptionOfferID: string, appAccountToken: string, nonce: string, timestamp: number): string {
         const payload = this.bundleId + '\u2063' +
             this.keyId + '\u2063' +
             productIdentifier + '\u2063' +
             subscriptionOfferID + '\u2063' +
-            applicationUsername.toLowerCase()  + '\u2063'+
+            appAccountToken.toLowerCase()  + '\u2063'+
             nonce.toLowerCase() + '\u2063' +
             timestamp;
         const sign = createSign('SHA256')
diff --git a/tests/unit-tests/promotional_offer_signature_creator.test.ts b/tests/unit-tests/promotional_offer_signature_creator.test.ts
index f577ab5..87d9a59 100644
--- a/tests/unit-tests/promotional_offer_signature_creator.test.ts
+++ b/tests/unit-tests/promotional_offer_signature_creator.test.ts
@@ -7,7 +7,7 @@ import { readFile } from "../util"
 describe('Promotional Offer Signature Creation Test', () => {
     it('should create a non-null signature', async () => {
         const signatureCreator = new PromotionalOfferSignatureCreator(readFile('tests/resources/certs/testSigningKey.p8'), "keyId", "bundleId");
-        const signature = signatureCreator.createSignature('productId', 'offerId', 'applicationUsername', "20fba8a0-2b80-4a7d-a17f-85c1854727f8", 1698148900000)
+        const signature = signatureCreator.createSignature('productId', 'offerId', 'appAccountToken', "20fba8a0-2b80-4a7d-a17f-85c1854727f8", 1698148900000)
         expect(signature).toBeTruthy()
     })
 })
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