diff --git a/.github/workflows/terraform-test.yml b/.github/workflows/terraform-test.yml
index 19c9e1e..36ed705 100644
--- a/.github/workflows/terraform-test.yml
+++ b/.github/workflows/terraform-test.yml
@@ -28,7 +28,7 @@ jobs:
       - name: Setup Terraform
         uses: hashicorp/setup-terraform@b9cd54a3c349d3f38e8881555d616ced269862dd # v3
         with:
-          terraform_version: "1.15.1"
+          terraform_version: "1.15.4"
           terraform_wrapper: false
 
       - name: Terraform Format Check
diff --git a/docs/how-to/develop-this-module.md b/docs/how-to/develop-this-module.md
index 1f9954d..f4613c1 100644
--- a/docs/how-to/develop-this-module.md
+++ b/docs/how-to/develop-this-module.md
@@ -4,7 +4,7 @@
 
 Install the same pinned tools used by CI:
 
-- Terraform 1.15.1
+- Terraform 1.15.4
 - TFLint 0.59.1
 - terraform-docs 0.20.0
 - OPA 1.10.0
diff --git a/terraform/versions.tf b/terraform/versions.tf
index bbcd5d6..17921e2 100644
--- a/terraform/versions.tf
+++ b/terraform/versions.tf
@@ -1,6 +1,6 @@
 terraform {
   # Pin Terraform exactly per org ADR 0005.
-  required_version = "= 1.15.1"
+  required_version = "= 1.15.4"
 
   required_providers {
     github = {