diff --git a/CHANGELOG.md b/CHANGELOG.md
index a2a9b48..a15ff82 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,8 @@
 
 ## Latest
 
-* Registry response to module version download path must be 204, not 200, because the server returns empty body. Download link is passed by means of X-Terraform-Get response header. Both terraform and opentofu support that (in fact they do support both 200 and 204). None of the production registries use 204 at the moment.
+* Added X-Terraform-Version request header for module calls
+* Registry response to module version download path must be 204, not 200, because the server returns empty body. Download link is passed by means of X-Terraform-Get response header. Both terraform and opentofu support that (in fact they do support both 200 and 204).
 * Added response errors to the model.
 * Updated the regex for module download URL
 * Added release github action, publishing the resulting openapi specification.
diff --git a/model/module.smithy b/model/module.smithy
index 328e644..725d8bc 100644
--- a/model/module.smithy
+++ b/model/module.smithy
@@ -5,6 +5,7 @@ namespace tf.registry.module
 use tf.registry.errors#NotFound
 use tf.registry.shapes#NamespaceDef
 use tf.registry.shapes#SemVer
+use tf.registry.shapes#TFVersion
 use tf.registry.shapes#githubModuleDownloadURL
 
 resource Module {
@@ -26,6 +27,9 @@ operation GetModuleVersion {
 
 @input
 structure GetModuleVersionInput {
+    @httpHeader("X-Terraform-Version")
+    xterraformversion: TFVersion
+
     @required
     @httpLabel
     namespace: NamespaceDef = "terraform-aws-modules"
@@ -63,6 +67,9 @@ operation ListModuleVersions {
 
 @input
 structure ListModuleVersionsInput {
+    @httpHeader("X-Terraform-Version")
+    xterraformversion: TFVersion
+
     @required
     @httpLabel
     namespace: NamespaceDef = "terraform-aws-modules"
diff --git a/model/shapes.smithy b/model/shapes.smithy
index 875efd5..6f195de 100644
--- a/model/shapes.smithy
+++ b/model/shapes.smithy
@@ -36,3 +36,10 @@ string NamespaceDef
 // semver
 @pattern("^(([0-9]{1}|[1-9][0-9])\\.){2}([0-9]{1}|[1-9][0-9]{1,2})$")
 string SemVer
+
+// terraform version
+// semver | semver-beta
+@pattern(
+    "^((([0-9]{1}|[1-9][0-9])\\.){2}([0-9]{1}|[1-9][0-9]{1,2}))$|(([0-9]{1}|[1-9][0-9])\\.){2}([0-9]{1}|[1-9][0-9]{1,2})-\\w+$"
+)
+string TFVersion