diff --git a/README.md b/README.md
index 1da192f..b6c38d2 100644
--- a/README.md
+++ b/README.md
@@ -164,6 +164,7 @@ resource "aws_rds_cluster_parameter_group" "aurora_cluster_postgres96_parameter_
 
 | Name | Description | Type | Default | Required |
 |------|-------------|:----:|:-----:|:-----:|
+| allow_major_version_upgrade | Determines whether major engine upgrades can be performed | string | `false` | no |
 | apply_immediately | Determines whether or not any DB modifications are applied immediately, or during the maintenance window | string | `false` | no |
 | auto_minor_version_upgrade | Determines whether minor engine upgrades will be performed automatically in the maintenance window | string | `true` | no |
 | azs | List of AZs to use | list | - | yes |
diff --git a/main.tf b/main.tf
index fb5284e..e31c45f 100644
--- a/main.tf
+++ b/main.tf
@@ -244,6 +244,7 @@ resource "aws_rds_cluster" "default" {
   apply_immediately               = var.apply_immediately
   db_cluster_parameter_group_name = var.db_cluster_parameter_group_name
   deletion_protection             = var.deletion_protection
+  allow_major_version_upgrade     = var.allow_major_version_upgrade
 }
 
 // Geneate an ID when an environment is initialised
diff --git a/variables.tf b/variables.tf
index ce0ecaf..a77037a 100644
--- a/variables.tf
+++ b/variables.tf
@@ -236,3 +236,9 @@ variable "performance_insights_enabled" {
   description = "Whether to enable Performance Insights"
 }
 
+variable "allow_major_version_upgrade" {
+  type        = string
+  default     = false
+  description = "Whether to allow major version upgrades"
+}
+