diff --git a/vpc-transit-gateway-association/peer/README.md b/vpc-transit-gateway-association/peer/README.md
index cdbf49b..279553f 100644
--- a/vpc-transit-gateway-association/peer/README.md
+++ b/vpc-transit-gateway-association/peer/README.md
@@ -235,7 +235,7 @@ No modules.
 | <a name="input_override_prefixes"></a> [override\_prefixes](#input\_override\_prefixes) | Override built-in prefixes by component. This should be used primarily for common infrastructure things | `map(string)` | `{}` | no |
 | <a name="input_private_route_table_ids"></a> [private\_route\_table\_ids](#input\_private\_route\_table\_ids) | Map of private route table IDs (which exclude the attachment subnets) | `map(string)` | `{}` | no |
 | <a name="input_private_subnets_ids"></a> [private\_subnets\_ids](#input\_private\_subnets\_ids) | List of private subnet objects including: subnet, label, availability\_zone, id | <pre>list(object({<br/>    subnet            = string<br/>    label             = string<br/>    availability_zone = string<br/>    id                = string<br/>  }))</pre> | `[]` | no |
-| <a name="input_propagate_all_route_table_names"></a> [propagate\_all\_route\_table\_names](#input\_propagate\_all\_route\_table\_names) | List of route table names to propagate routes into for every attachment | `list` | <pre>[<br/>  "services",<br/>  "inter-region"<br/>]</pre> | no |
+| <a name="input_propagate_all_route_table_names"></a> [propagate\_all\_route\_table\_names](#input\_propagate\_all\_route\_table\_names) | List of route table names to propagate routes into for every attachment | `list(string)` | <pre>[<br/>  "services",<br/>  "inter-region"<br/>]</pre> | no |
 | <a name="input_route_prefix_list_name"></a> [route\_prefix\_list\_name](#input\_route\_prefix\_list\_name) | Shared prefix list name used for routing to TGW.  It is comprised of all of the network CIDR blocks in AWS using TGW. | `string` | `"transit-gateway.prod"` | no |
 | <a name="input_route_table_label"></a> [route\_table\_label](#input\_route\_table\_label) | Route table lable for the attachment subnets | `string` | `"attachment"` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | AWS Tags to apply to appropriate resources (S3, KMS).  Do not include safeguard tags here, use the data\_safeguard field for such things. | `map(string)` | `{}` | no |
diff --git a/vpc-transit-gateway-association/peer/variables.tf b/vpc-transit-gateway-association/peer/variables.tf
index 1556631..ba6272a 100644
--- a/vpc-transit-gateway-association/peer/variables.tf
+++ b/vpc-transit-gateway-association/peer/variables.tf
@@ -60,7 +60,7 @@ variable "private_route_table_ids" {
 
 variable "propagate_all_route_table_names" {
   description = "List of route table names to propagate routes into for every attachment"
-  type        = list
+  type        = list(string)
   default     = ["services", "inter-region"]
 
   validation {
diff --git a/vpc-transit-gateway-association/self/README.md b/vpc-transit-gateway-association/self/README.md
index 6ad6130..5913cc6 100644
--- a/vpc-transit-gateway-association/self/README.md
+++ b/vpc-transit-gateway-association/self/README.md
@@ -265,7 +265,7 @@ module "vpc_tgw_self" {
 | <a name="input_override_prefixes"></a> [override\_prefixes](#input\_override\_prefixes) | Override built-in prefixes by component. This should be used primarily for common infrastructure things | `map(string)` | `{}` | no |
 | <a name="input_private_route_table_ids"></a> [private\_route\_table\_ids](#input\_private\_route\_table\_ids) | Map of private route table IDs (which exclude the attachment subnets) | `map(string)` | `{}` | no |
 | <a name="input_private_subnets_ids"></a> [private\_subnets\_ids](#input\_private\_subnets\_ids) | List of private subnet objects including: subnet, label, availability\_zone, id | <pre>list(object({<br/>    subnet            = string<br/>    label             = string<br/>    availability_zone = string<br/>    id                = string<br/>  }))</pre> | `[]` | no |
-| <a name="input_propagate_all_route_table_names"></a> [propagate\_all\_route\_table\_names](#input\_propagate\_all\_route\_table\_names) | List of route table names to propagate routes into for every attachment | `list` | <pre>[<br/>  "services",<br/>  "inter-region"<br/>]</pre> | no |
+| <a name="input_propagate_all_route_table_names"></a> [propagate\_all\_route\_table\_names](#input\_propagate\_all\_route\_table\_names) | List of route table names to propagate routes into for every attachment | `list(string)` | <pre>[<br/>  "services",<br/>  "inter-region"<br/>]</pre> | no |
 | <a name="input_route_prefix_list_name"></a> [route\_prefix\_list\_name](#input\_route\_prefix\_list\_name) | Shared prefix list name used for routing to TGW.  It is comprised of all of the network CIDR blocks in AWS using TGW. | `string` | `"transit-gateway.prod"` | no |
 | <a name="input_route_table_label"></a> [route\_table\_label](#input\_route\_table\_label) | Route table lable for the attachment subnets | `string` | `"attachment"` | no |
 | <a name="input_tags"></a> [tags](#input\_tags) | AWS Tags to apply to appropriate resources (S3, KMS).  Do not include safeguard tags here, use the data\_safeguard field for such things. | `map(string)` | `{}` | no |
diff --git a/vpc-transit-gateway-association/self/variables.tf b/vpc-transit-gateway-association/self/variables.tf
index 0fedcf9..3f790e4 100644
--- a/vpc-transit-gateway-association/self/variables.tf
+++ b/vpc-transit-gateway-association/self/variables.tf
@@ -66,7 +66,7 @@ variable "transit_gateway_environments" {
 
 variable "propagate_all_route_table_names" {
   description = "List of route table names to propagate routes into for every attachment"
-  type        = list
+  type        = list(string)
   default     = ["services", "inter-region"]
 
   validation {