diff --git a/app/middleware/get-service-and-gateway-account.middleware.js b/app/middleware/get-service-and-gateway-account.middleware.js
index 7c11ab8e12..63e641f707 100644
--- a/app/middleware/get-service-and-gateway-account.middleware.js
+++ b/app/middleware/get-service-and-gateway-account.middleware.js
@@ -90,7 +90,10 @@ module.exports = async function getServiceAndGatewayAccount (req, res, next) {
           req.account = gatewayAccount
           // TODO: To be removed once URLs are updated to use the format /service/:serviceExternalId/account/:gatewayAccountExternalId/xxx.
           // Currently authService.getCurrentGatewayAccountId() sets below if account is available on session or derives one from user services.
-          req.gateway_account = { currentGatewayAccountId: gatewayAccount.gateway_account_id, currentGatewayAccountExternalId: gatewayAccount.external_id }
+          req.gateway_account = {
+            currentGatewayAccountId: gatewayAccount.gateway_account_id && String(gatewayAccount.gateway_account_id),
+            currentGatewayAccountExternalId: gatewayAccount.external_id
+          }
         }
       }
 
diff --git a/test/unit/middleware/get-service-and-gateway-account.middleware.test.js b/test/unit/middleware/get-service-and-gateway-account.middleware.test.js
index 2c8f2d0891..6e174b4e6f 100644
--- a/test/unit/middleware/get-service-and-gateway-account.middleware.test.js
+++ b/test/unit/middleware/get-service-and-gateway-account.middleware.test.js
@@ -86,7 +86,7 @@ describe('middleware: getGatewayAccountAndService', () => {
     expect(req.service.externalId).to.equal('some-service-external-id')
     expect(req.service.hasCardGatewayAccount).to.equal(true)
 
-    expect(req.gateway_account.currentGatewayAccountId).to.equal(1)
+    expect(req.gateway_account.currentGatewayAccountId).to.equal('1')
   })
   it('should error, if both gateway account external ID and service external ID cannot be resolved', async () => {
     const getGatewayAccountAndService = setupGetGatewayAccountAndService(1, 'some-gateway-external-id', 'worldpay', 'some-service-external-id')