diff --git a/modules/mpc-backup-key/README.md b/modules/mpc-backup-key/README.md
index 8077dca..dd38d45 100644
--- a/modules/mpc-backup-key/README.md
+++ b/modules/mpc-backup-key/README.md
@@ -40,5 +40,7 @@ No modules.
 
 ## Outputs
 
-No outputs.
+| Name | Description |
+|------|-------------|
+| <a name="output_kms_key_arn"></a> [kms\_key\_arn](#output\_kms\_key\_arn) | The ARN of the KMS key |
 <!-- END_TF_DOCS -->
diff --git a/modules/mpc-backup-key/outputs.tf b/modules/mpc-backup-key/outputs.tf
index e69de29..6702923 100644
--- a/modules/mpc-backup-key/outputs.tf
+++ b/modules/mpc-backup-key/outputs.tf
@@ -0,0 +1,4 @@
+output "kms_key_arn" {
+  description = "The ARN of the KMS key"
+  value       = aws_kms_key.this_backup.arn
+}