diff --git a/terraform-aws-wireguard/README.md b/terraform-aws-wireguard/README.md
index 531773d..a4e7c66 100644
--- a/terraform-aws-wireguard/README.md
+++ b/terraform-aws-wireguard/README.md
@@ -64,7 +64,7 @@ resource "aws_route" "wireguard_instance" {
   for_each = toset(local.route_table_ids)
 
   route_table_id         = each.value
-  destination_cidr_block = module.wireguard.wireguard_interface_address
+  destination_cidr_block = module.wireguard.wireguard_cidr
   network_interface_id   = module.wireguard.aws_network_interface.id
 }
 ```
@@ -135,7 +135,7 @@ No modules.
 | <a name="output_launch_template"></a> [launch\_template](#output\_launch\_template) | Launch template of NAT instance |
 | <a name="output_network_interface"></a> [network\_interface](#output\_network\_interface) | Network interface of WireGuard interface instance |
 | <a name="output_security_group"></a> [security\_group](#output\_security\_group) | Security group of WireGuard interface instance |
-| <a name="output_wireguard_interface_address"></a> [wireguard\_interface\_address](#output\_wireguard\_interface\_address) | WireGuard interface address |
+| <a name="output_wireguard_cidr"></a> [wireguard\_cidr](#output\_wireguard\_cidr) | WireGuard CIDR |
 <!-- END_TF_DOCS -->
 
 ## Note
diff --git a/terraform-aws-wireguard/output.tf b/terraform-aws-wireguard/output.tf
index 7b3445d..8dacbe5 100644
--- a/terraform-aws-wireguard/output.tf
+++ b/terraform-aws-wireguard/output.tf
@@ -28,7 +28,7 @@ output "autoscaling_group" {
   description = "Autoscaling group of NAT instance"
 }
 
-output "wireguard_interface_address" {
-  value       = var.wireguard_interface_address
-  description = "WireGuard interface address"
+output "wireguard_cidr" {
+  value       = cidrsubnet(var.wireguard_cidr, 0, 0)
+  description = "WireGuard CIDR"
 }
\ No newline at end of file