diff --git a/appgateways/appgw-qs/outputs.tf b/appgateways/appgw-qs/outputs.tf
index 921ea92..4069539 100644
--- a/appgateways/appgw-qs/outputs.tf
+++ b/appgateways/appgw-qs/outputs.tf
@@ -11,5 +11,5 @@ output "appgw_public_ip" {
 }
 
 output "appgw_backend_address_pool_0_id" {
-  value = azurerm_application_gateway.qmi-app-gw.backend_address_pool[0]? azurerm_application_gateway.qmi-app-gw.backend_address_pool[0].id : null
+  value = (azurerm_application_gateway.qmi-app-gw.backend_address_pool != null && azurerm_application_gateway.qmi-app-gw.backend_address_pool[0].id != null)? azurerm_application_gateway.qmi-app-gw.backend_address_pool[0].id : null
 }