diff --git a/src/FuturePayService.ts b/src/FuturePayService.ts
index 99df67d..1e2a999 100644
--- a/src/FuturePayService.ts
+++ b/src/FuturePayService.ts
@@ -7,7 +7,7 @@ export class FuturePayService {
         this.url = isTestEnvironment ? "https://secure-test.worldpay.com/wcc/purchase" : "https://secure.worldpay.com/wcc/purchase";
     }
 
-    initiateAgreement(agreement: Agreement): Promise<void> {
+    initiateAgreement(agreement: Agreement, callbackUrl: string | null = null): Promise<void> {
         var formInputsHtml = "";
 
         for (var key in agreement) {
@@ -16,6 +16,10 @@ export class FuturePayService {
             }
         }
 
+        if (callbackUrl) {
+            formInputsHtml += `<input type='hidden' name='MC_callback' value='${callbackUrl}'></input>`;
+        }
+
         if (document) {
             var form = document.createElement("form");
             form.setAttribute("method", "post");