diff --git a/vpc-transit-gateway-association/README.md b/vpc-transit-gateway-association/README.md
index ab5a894..d62f21d 100644
--- a/vpc-transit-gateway-association/README.md
+++ b/vpc-transit-gateway-association/README.md
@@ -15,7 +15,8 @@ section TGW setup, consisting of data (required), self, and peer (remote(s)).  T
 * [peer](peer/)
   * creates static routes for transit gateway route tables in a peer region
 
-Use of this set of modules and configuration requires Terraform 1.x.
+Use of this set of modules and configuration requires Terraform 1.x and the Terraform Provider v4.x.  If you have the AWS provider pinned with a `version = "~> 3.66"` statement
+you'll ned to change that to `version = ">= 4.0"`.
 
 # Setup