diff --git a/main.go b/main.go
index 204fff5..8e8fee6 100644
--- a/main.go
+++ b/main.go
@@ -117,7 +117,7 @@ func addLicense(path string, fmode os.FileMode, typ string, data *copyrightData)
 		return nil
 	case ".c", ".h":
 		lic, err = prefix(typ, data, "/*", " * ", " */")
-	case ".js", ".css":
+	case ".js", ".css", ".tf":
 		lic, err = prefix(typ, data, "/**", " * ", " */")
 	case ".cc", ".cpp", ".cs", ".go", ".hh", ".hpp", ".java", ".m", ".mm", ".proto", ".rs", ".scala", ".swift", ".dart":
 		lic, err = prefix(typ, data, "", "// ", "")
diff --git a/testdata/expected/file.tf b/testdata/expected/file.tf
new file mode 100644
index 0000000..726f114
--- /dev/null
+++ b/testdata/expected/file.tf
@@ -0,0 +1,17 @@
+/**
+ * Copyright 2016 Google Inc.
+ * 
+ * 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.
+ */
+
+resource "null_resource" "dummy" {}
diff --git a/testdata/initial/file.tf b/testdata/initial/file.tf
new file mode 100644
index 0000000..06d2b2a
--- /dev/null
+++ b/testdata/initial/file.tf
@@ -0,0 +1 @@
+resource "null_resource" "dummy" {}