diff --git a/packages/sdk/src/HeadlessUniversalCheckout/Managers/VaultManager.ts b/packages/sdk/src/HeadlessUniversalCheckout/Managers/VaultManager.ts
index 3df633e1f..b6e4285d4 100644
--- a/packages/sdk/src/HeadlessUniversalCheckout/Managers/VaultManager.ts
+++ b/packages/sdk/src/HeadlessUniversalCheckout/Managers/VaultManager.ts
@@ -88,10 +88,13 @@ class PrimerHeadlessUniversalCheckoutVaultManager {
     }
 }
 
+// Convert accountNumberLastFourDigits to accountNumberLast4Digits when present
+// Overcomes an iOS limitation of toJsonObject()
 function sanitizePaymentMethods(paymentMethods: VaultedPaymentMethod[]): VaultedPaymentMethod[] {
     return paymentMethods.map(method => {
-        if (method.paymentInstrumentData?.accountNumberLastFourDigits !== undefined) {
-            const { accountNumberLastFourDigits, ...rest } = method.paymentInstrumentData;
+        const unwrappedInstrumentData = method.paymentInstrumentData as any;
+        if (unwrappedInstrumentData?.accountNumberLastFourDigits !== undefined) {
+            const { accountNumberLastFourDigits, ...rest } = unwrappedInstrumentData;
             return {
                 ...method,
                 paymentInstrumentData: {
@@ -104,4 +107,5 @@ function sanitizePaymentMethods(paymentMethods: VaultedPaymentMethod[]): Vaulted
     });
 }
 
+
 export default PrimerHeadlessUniversalCheckoutVaultManager;