diff --git a/action.go b/action.go
index 51c4c83..c74f7e6 100644
--- a/action.go
+++ b/action.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 // Action is a valid action type for a resource change.
diff --git a/cmd/round-trip-dumper/main.go b/cmd/round-trip-dumper/main.go
index b07e404..92c2270 100644
--- a/cmd/round-trip-dumper/main.go
+++ b/cmd/round-trip-dumper/main.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package main
 
 import (
diff --git a/config.go b/config.go
index 5ebe4bc..e8ea638 100644
--- a/config.go
+++ b/config.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/config_test.go b/config_test.go
index 1cd17fa..c0cf1e0 100644
--- a/config_test.go
+++ b/config_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/expression.go b/expression.go
index 8a39fac..5ecb15c 100644
--- a/expression.go
+++ b/expression.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import "encoding/json"
diff --git a/expression_test.go b/expression_test.go
index aea1eea..1fb74ef 100644
--- a/expression_test.go
+++ b/expression_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/metadata.go b/metadata.go
index 70d7ce4..eb52577 100644
--- a/metadata.go
+++ b/metadata.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/metadata_test.go b/metadata_test.go
index 1bc0072..9938a09 100644
--- a/metadata_test.go
+++ b/metadata_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/parse_test.go b/parse_test.go
index 78495ef..79c9a66 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/plan.go b/plan.go
index 6cfd533..cbbf186 100644
--- a/plan.go
+++ b/plan.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/plan_test.go b/plan_test.go
index 003e966..c74826d 100644
--- a/plan_test.go
+++ b/plan_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/sanitize/copy.go b/sanitize/copy.go
index 27991fd..01913a1 100644
--- a/sanitize/copy.go
+++ b/sanitize/copy.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/copy_test.go b/sanitize/copy_test.go
index 63bff6c..be7d6a4 100644
--- a/sanitize/copy_test.go
+++ b/sanitize/copy_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_change.go b/sanitize/sanitize_change.go
index 3396438..086cca1 100644
--- a/sanitize/sanitize_change.go
+++ b/sanitize/sanitize_change.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_change_test.go b/sanitize/sanitize_change_test.go
index 775a1f4..0741b2a 100644
--- a/sanitize/sanitize_change_test.go
+++ b/sanitize/sanitize_change_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_plan.go b/sanitize/sanitize_plan.go
index 6d009f0..d03b8fa 100644
--- a/sanitize/sanitize_plan.go
+++ b/sanitize/sanitize_plan.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_plan_test.go b/sanitize/sanitize_plan_test.go
index 18ad5c3..9506423 100644
--- a/sanitize/sanitize_plan_test.go
+++ b/sanitize/sanitize_plan_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_plan_variables.go b/sanitize/sanitize_plan_variables.go
index 7d86a12..b800ebb 100644
--- a/sanitize/sanitize_plan_variables.go
+++ b/sanitize/sanitize_plan_variables.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_plan_variables_test.go b/sanitize/sanitize_plan_variables_test.go
index 19164ce..482b181 100644
--- a/sanitize/sanitize_plan_variables_test.go
+++ b/sanitize/sanitize_plan_variables_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_state.go b/sanitize/sanitize_state.go
index 3aba29b..e1fe1a7 100644
--- a/sanitize/sanitize_state.go
+++ b/sanitize/sanitize_state.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/sanitize/sanitize_state_test.go b/sanitize/sanitize_state_test.go
index 7ca194a..ac7d501 100644
--- a/sanitize/sanitize_state_test.go
+++ b/sanitize/sanitize_state_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package sanitize
 
 import (
diff --git a/schemas.go b/schemas.go
index f7c8abd..64f87d8 100644
--- a/schemas.go
+++ b/schemas.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/schemas_test.go b/schemas_test.go
index a02ffba..5044559 100644
--- a/schemas_test.go
+++ b/schemas_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/state.go b/state.go
index 3c3f6a4..02f0dc6 100644
--- a/state.go
+++ b/state.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/state_test.go b/state_test.go
index c1b9fa4..dee9021 100644
--- a/state_test.go
+++ b/state_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/testdata/013_module_depends_on/main.tf b/testdata/013_module_depends_on/main.tf
index 5142ecf..69bbfad 100644
--- a/testdata/013_module_depends_on/main.tf
+++ b/testdata/013_module_depends_on/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
     source = "vancluever/module/null"
 
diff --git a/testdata/110_basic/foo/main.tf b/testdata/110_basic/foo/main.tf
index 6c96638..c982366 100644
--- a/testdata/110_basic/foo/main.tf
+++ b/testdata/110_basic/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 terraform {
   required_providers {
     null = {
diff --git a/testdata/110_basic/module.tf b/testdata/110_basic/module.tf
index 26a3ebe..748acf8 100644
--- a/testdata/110_basic/module.tf
+++ b/testdata/110_basic/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/110_basic/outputs.tf b/testdata/110_basic/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/110_basic/outputs.tf
+++ b/testdata/110_basic/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/110_basic/providers.tf b/testdata/110_basic/providers.tf
index e2b7d2e..ff1a6f2 100644
--- a/testdata/110_basic/providers.tf
+++ b/testdata/110_basic/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 terraform {
   required_providers {
     null = {
diff --git a/testdata/110_basic/resources.tf b/testdata/110_basic/resources.tf
index d0d408a..8b56d9b 100644
--- a/testdata/110_basic/resources.tf
+++ b/testdata/110_basic/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/110_basic/variables.tf b/testdata/110_basic/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/110_basic/variables.tf
+++ b/testdata/110_basic/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/110_sensitive_values/foo/main.tf b/testdata/110_sensitive_values/foo/main.tf
index 7e23c1e..9d5bbd8 100644
--- a/testdata/110_sensitive_values/foo/main.tf
+++ b/testdata/110_sensitive_values/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "bar" {
   type = string
 }
diff --git a/testdata/110_sensitive_values/module.tf b/testdata/110_sensitive_values/module.tf
index 26a3ebe..748acf8 100644
--- a/testdata/110_sensitive_values/module.tf
+++ b/testdata/110_sensitive_values/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/110_sensitive_values/outputs.tf b/testdata/110_sensitive_values/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/110_sensitive_values/outputs.tf
+++ b/testdata/110_sensitive_values/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/110_sensitive_values/providers.tf b/testdata/110_sensitive_values/providers.tf
index 502945b..23ef26c 100644
--- a/testdata/110_sensitive_values/providers.tf
+++ b/testdata/110_sensitive_values/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 terraform {
   required_providers {
     null = {
diff --git a/testdata/110_sensitive_values/resources.tf b/testdata/110_sensitive_values/resources.tf
index d0d408a..8b56d9b 100644
--- a/testdata/110_sensitive_values/resources.tf
+++ b/testdata/110_sensitive_values/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/110_sensitive_values/variables.tf b/testdata/110_sensitive_values/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/110_sensitive_values/variables.tf
+++ b/testdata/110_sensitive_values/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/120_basic/foo/main.tf b/testdata/120_basic/foo/main.tf
index 6c96638..c982366 100644
--- a/testdata/120_basic/foo/main.tf
+++ b/testdata/120_basic/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 terraform {
   required_providers {
     null = {
diff --git a/testdata/120_basic/module.tf b/testdata/120_basic/module.tf
index 26a3ebe..748acf8 100644
--- a/testdata/120_basic/module.tf
+++ b/testdata/120_basic/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/120_basic/outputs.tf b/testdata/120_basic/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/120_basic/outputs.tf
+++ b/testdata/120_basic/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/120_basic/providers.tf b/testdata/120_basic/providers.tf
index e2b7d2e..ff1a6f2 100644
--- a/testdata/120_basic/providers.tf
+++ b/testdata/120_basic/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 terraform {
   required_providers {
     null = {
diff --git a/testdata/120_basic/resources.tf b/testdata/120_basic/resources.tf
index d0d408a..8b56d9b 100644
--- a/testdata/120_basic/resources.tf
+++ b/testdata/120_basic/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/120_basic/variables.tf b/testdata/120_basic/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/120_basic/variables.tf
+++ b/testdata/120_basic/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/basic/foo/main.tf b/testdata/basic/foo/main.tf
index 8c48a85..ffa6741 100644
--- a/testdata/basic/foo/main.tf
+++ b/testdata/basic/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "bar" {
   type = "string"
 }
diff --git a/testdata/basic/module.tf b/testdata/basic/module.tf
index 236fdac..0093efe 100644
--- a/testdata/basic/module.tf
+++ b/testdata/basic/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/basic/outputs.tf b/testdata/basic/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/basic/outputs.tf
+++ b/testdata/basic/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/basic/providers.tf b/testdata/basic/providers.tf
index 4d48120..121e8e7 100644
--- a/testdata/basic/providers.tf
+++ b/testdata/basic/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 provider "null" {}
 
 provider "aws" {
diff --git a/testdata/basic/resources.tf b/testdata/basic/resources.tf
index 1d4a8e8..2584f74 100644
--- a/testdata/basic/resources.tf
+++ b/testdata/basic/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/basic/variables.tf b/testdata/basic/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/basic/variables.tf
+++ b/testdata/basic/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/config_resource_depends_on/main.tf b/testdata/config_resource_depends_on/main.tf
index 4eede79..aeb2abb 100644
--- a/testdata/config_resource_depends_on/main.tf
+++ b/testdata/config_resource_depends_on/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {}
 
 resource "null_resource" "bar" {
diff --git a/testdata/deep_module/foo/bar/main.tf b/testdata/deep_module/foo/bar/main.tf
index 87b7dc3..ca0b1cd 100644
--- a/testdata/deep_module/foo/bar/main.tf
+++ b/testdata/deep_module/foo/bar/main.tf
@@ -1 +1,4 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "baz" {}
diff --git a/testdata/deep_module/foo/main.tf b/testdata/deep_module/foo/main.tf
index 88d61ea..7ed7c97 100644
--- a/testdata/deep_module/foo/main.tf
+++ b/testdata/deep_module/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "bar" {
   source = "./bar"
 }
diff --git a/testdata/deep_module/main.tf b/testdata/deep_module/main.tf
index 9ae1dbe..0227248 100644
--- a/testdata/deep_module/main.tf
+++ b/testdata/deep_module/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 }
diff --git a/testdata/explicit_null/main.tf b/testdata/explicit_null/main.tf
index 0970874..0e91c13 100644
--- a/testdata/explicit_null/main.tf
+++ b/testdata/explicit_null/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "one" {
   type = "string"
 }
diff --git a/testdata/explicit_null/terraform.tfvars b/testdata/explicit_null/terraform.tfvars
index 6180694..3d12b95 100644
--- a/testdata/explicit_null/terraform.tfvars
+++ b/testdata/explicit_null/terraform.tfvars
@@ -1 +1,4 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 one = "two"
diff --git a/testdata/has_changes/foo/main.tf b/testdata/has_changes/foo/main.tf
index f3d0b00..bb2a83c 100644
--- a/testdata/has_changes/foo/main.tf
+++ b/testdata/has_changes/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "bar" {
   type = "string"
 }
diff --git a/testdata/has_changes/module.tf b/testdata/has_changes/module.tf
index 236fdac..0093efe 100644
--- a/testdata/has_changes/module.tf
+++ b/testdata/has_changes/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/has_changes/outputs.tf b/testdata/has_changes/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/has_changes/outputs.tf
+++ b/testdata/has_changes/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/has_changes/providers.tf b/testdata/has_changes/providers.tf
index 4d48120..121e8e7 100644
--- a/testdata/has_changes/providers.tf
+++ b/testdata/has_changes/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 provider "null" {}
 
 provider "aws" {
diff --git a/testdata/has_changes/resources.tf b/testdata/has_changes/resources.tf
index 1d4a8e8..2584f74 100644
--- a/testdata/has_changes/resources.tf
+++ b/testdata/has_changes/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/has_changes/variables.tf b/testdata/has_changes/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/has_changes/variables.tf
+++ b/testdata/has_changes/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/nested_config_keys/main.tf b/testdata/nested_config_keys/main.tf
index 4a43a15..d9d3000 100644
--- a/testdata/nested_config_keys/main.tf
+++ b/testdata/nested_config_keys/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 provider "aws" {
   region = "us-east-1"
 }
diff --git a/testdata/no_changes/foo/main.tf b/testdata/no_changes/foo/main.tf
index f3d0b00..bb2a83c 100644
--- a/testdata/no_changes/foo/main.tf
+++ b/testdata/no_changes/foo/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "bar" {
   type = "string"
 }
diff --git a/testdata/no_changes/module.tf b/testdata/no_changes/module.tf
index 236fdac..0093efe 100644
--- a/testdata/no_changes/module.tf
+++ b/testdata/no_changes/module.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "foo" {
   source = "./foo"
 
diff --git a/testdata/no_changes/outputs.tf b/testdata/no_changes/outputs.tf
index 1e2a453..c2d5312 100644
--- a/testdata/no_changes/outputs.tf
+++ b/testdata/no_changes/outputs.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 output "foo" {
   sensitive = true
   value     = "bar"
diff --git a/testdata/no_changes/providers.tf b/testdata/no_changes/providers.tf
index 4d48120..121e8e7 100644
--- a/testdata/no_changes/providers.tf
+++ b/testdata/no_changes/providers.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 provider "null" {}
 
 provider "aws" {
diff --git a/testdata/no_changes/resources.tf b/testdata/no_changes/resources.tf
index 1d4a8e8..2584f74 100644
--- a/testdata/no_changes/resources.tf
+++ b/testdata/no_changes/resources.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {
   triggers = {
     foo = "bar"
diff --git a/testdata/no_changes/variables.tf b/testdata/no_changes/variables.tf
index 3964e7a..3aaf377 100644
--- a/testdata/no_changes/variables.tf
+++ b/testdata/no_changes/variables.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 variable "foo" {
   description = "foobar"
   default     = "bar"
diff --git a/testdata/output_depends_on/main.tf b/testdata/output_depends_on/main.tf
index c3dc56c..88b1b84 100644
--- a/testdata/output_depends_on/main.tf
+++ b/testdata/output_depends_on/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 resource "null_resource" "foo" {}
 
 resource "null_resource" "bar" {}
diff --git a/testdata/provider_version/main.tf b/testdata/provider_version/main.tf
index 8200c58..1f96cf8 100644
--- a/testdata/provider_version/main.tf
+++ b/testdata/provider_version/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 provider "null" {
   version = "~> 2.1"
 }
diff --git a/testdata/registry_module/main.tf b/testdata/registry_module/main.tf
index f512d2c..c8c05d8 100644
--- a/testdata/registry_module/main.tf
+++ b/testdata/registry_module/main.tf
@@ -1,3 +1,6 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
 module "module" {
   source  = "vancluever/module/null"
   version = "~> 1.0.1"
diff --git a/tfjson.go b/tfjson.go
index 55f9ac4..3a78a4f 100644
--- a/tfjson.go
+++ b/tfjson.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 // Package tfjson is a de-coupled helper library containing types for
 // the plan format output by "terraform show -json" command. This
 // command is designed for the export of Terraform plan data in
diff --git a/validate.go b/validate.go
index 97b82d0..53652ef 100644
--- a/validate.go
+++ b/validate.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/validate_test.go b/validate_test.go
index c876045..6b7860f 100644
--- a/validate_test.go
+++ b/validate_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (
diff --git a/version.go b/version.go
index 16f0a85..7516ad6 100644
--- a/version.go
+++ b/version.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 // VersionOutput represents output from the version -json command
diff --git a/version_test.go b/version_test.go
index dcd7317..b935fbd 100644
--- a/version_test.go
+++ b/version_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package tfjson
 
 import (