diff --git a/main.go b/main.go
index 1f3c093..f5721e4 100644
--- a/main.go
+++ b/main.go
@@ -262,7 +262,7 @@ func licenseHeader(path string, tmpl *template.Template, data licenseData) ([]by
 		lic, err = executeTemplate(tmpl, data, "/*", " * ", " */")
 	case ".js", ".mjs", ".cjs", ".jsx", ".tsx", ".css", ".scss", ".sass", ".tf", ".ts":
 		lic, err = executeTemplate(tmpl, data, "/**", " * ", " */")
-	case ".cc", ".cpp", ".cs", ".go", ".hh", ".hpp", ".java", ".m", ".mm", ".proto", ".rs", ".scala", ".swift", ".dart", ".groovy", ".kt", ".kts", ".v", ".sv":
+	case ".cc", ".cpp", ".cs", ".go", ".hcl", ".hh", ".hpp", ".java", ".m", ".mm", ".proto", ".rs", ".scala", ".swift", ".dart", ".groovy", ".kt", ".kts", ".v", ".sv":
 		lic, err = executeTemplate(tmpl, data, "", "// ", "")
 	case ".py", ".sh", ".yaml", ".yml", ".dockerfile", "dockerfile", ".rb", "gemfile", ".tcl", ".bzl":
 		lic, err = executeTemplate(tmpl, data, "", "# ", "")
diff --git a/main_test.go b/main_test.go
index 1202e71..c6ce68a 100644
--- a/main_test.go
+++ b/main_test.go
@@ -309,7 +309,7 @@ func TestLicenseHeader(t *testing.T) {
 			"/**\n * HYS\n */\n\n",
 		},
 		{
-			[]string{"f.cc", "f.cpp", "f.cs", "f.go", "f.hh", "f.hpp", "f.java", "f.m", "f.mm", "f.proto",
+			[]string{"f.cc", "f.cpp", "f.cs", "f.go", "f.hcl", "f.hh", "f.hpp", "f.java", "f.m", "f.mm", "f.proto",
 				"f.rs", "f.scala", "f.swift", "f.dart", "f.groovy", "f.kt", "f.kts", "f.v", "f.sv", "f.php"},
 			"// HYS\n\n",
 		},
diff --git a/testdata/expected/file.hcl b/testdata/expected/file.hcl
new file mode 100644
index 0000000..aeeeab9
--- /dev/null
+++ b/testdata/expected/file.hcl
@@ -0,0 +1,22 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+group "default" {
+  targets = ["build"]
+}
+
+target "build" {
+  dockerfile = "./Dockerfile"
+  output = ["type=docker"]
+}
diff --git a/testdata/initial/file.hcl b/testdata/initial/file.hcl
new file mode 100644
index 0000000..f3a4824
--- /dev/null
+++ b/testdata/initial/file.hcl
@@ -0,0 +1,8 @@
+group "default" {
+  targets = ["build"]
+}
+
+target "build" {
+  dockerfile = "./Dockerfile"
+  output = ["type=docker"]
+}