diff --git a/modules/security_hub/variables.tf b/modules/security_hub/variables.tf
index 5f747f3..062ef0a 100644
--- a/modules/security_hub/variables.tf
+++ b/modules/security_hub/variables.tf
@@ -1,5 +1,6 @@
 variable "account_id" {
   type        = string
+  default     = null
   description = "AWS Account ID"
 }