diff --git a/README.md b/README.md
index 32465f4..395f8dc 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,7 @@ MIT Licensed. See [LICENSE](https://github.com/terraform-aws-modules/terraform-a
 | cluster_version | Kubernetes version to use for the cluster. | string | `1.10` | no |
 | config_output_path | Determines where config files are placed if using configure_kubectl_session and you want config files to land outside the current working directory. | string | `./` | no |
 | configure_kubectl_session | Configure the current session's kubectl to use the instantiated cluster. | string | `false` | no |
+| ebs_optimized_workers | If left at default of true, will use ebs optimization if available on the given instance type. | string | `true` | no |
 | subnets | A list of subnets to associate with the cluster's underlying instances. | list | - | yes |
 | tags | A map of tags to add to all resources. | string | `<map>` | no |
 | vpc_id | VPC id where the cluster and other resources will be deployed. | string | - | yes |