diff --git a/vpc-transit-gateway-association/README.md b/vpc-transit-gateway-association/README.md
index 2383733..ab5a894 100644
--- a/vpc-transit-gateway-association/README.md
+++ b/vpc-transit-gateway-association/README.md
@@ -15,6 +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.
+
 # Setup
 
 Due to the nature of some of the data resources and `for_each` not being able to be determined properly, this is split into three