diff --git a/vpc-transit-gateway-association/self/routing.tf b/vpc-transit-gateway-association/self/routing.tf
index a8e0747..a022375 100644
--- a/vpc-transit-gateway-association/self/routing.tf
+++ b/vpc-transit-gateway-association/self/routing.tf
@@ -56,7 +56,7 @@ resource "aws_route" "gateway_ipv4" {
 }
 
 resource "aws_route" "gateway_vpn_ipv4" {
-  for_each = var.private_route_table_ids
+  for_each = var.vpn_route_prefix_list_name != null && var.data_input.vpn_prefix_list_id_ipv4 != null ? var.private_route_table_ids : {}
 
   route_table_id             = each.value
   destination_prefix_list_id = var.data_input.vpn_prefix_list_id_ipv4