diff --git a/main.tf b/main.tf
index 4605da9..fa5546a 100644
--- a/main.tf
+++ b/main.tf
@@ -83,6 +83,8 @@ resource "aws_elasticache_replication_group" "default" {
   # apply_immediately applies only to modifications in node type, engine version, and changing the number of nodes in a cluster.
   # Other modifications, such as changing the maintenance window, are applied immediately.
   # https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Clusters.Modify.html
+  auth_token                  = var.auth_token != "" ? var.auth_token : null
+
   apply_immediately = var.apply_immediately
 
   # A user-created description for the replication group.
diff --git a/variables.tf b/variables.tf
index 9be4257..8f47867 100644
--- a/variables.tf
+++ b/variables.tf
@@ -76,6 +76,12 @@ variable "transit_encryption_enabled" {
   description = "Whether to enable encryption in transit."
 }
 
+variable "auth_token" {
+  type        = string
+  description = "The password used to access a password protected server. Can be specified only if `transit_encryption_enabled = true`."
+  default     = ""
+}
+
 variable "apply_immediately" {
   default     = false
   type        = bool