diff --git a/README.md b/README.md
index 2392259..11887c5 100644
--- a/README.md
+++ b/README.md
@@ -13,10 +13,11 @@ to any file that already has one.
 ## usage
 
     addlicense [flags] pattern [pattern ...]
-    
+
     -c copyright holder (default "Google LLC.")
+    -f custom license file (no default)
     -l license type: apache, bsd, mit (default "apache")
-    -y year (default 2016)
+    -y year (default "2018")
 
 The pattern argument can be provided multiple times, and may also refer
 to single files.
diff --git a/main.go b/main.go
index 90a0445..21e317d 100644
--- a/main.go
+++ b/main.go
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
@@ -135,16 +135,16 @@ func walk(ch chan<- *file, start string) {
 func addLicense(path string, fmode os.FileMode, tmpl *template.Template, data *copyrightData) error {
 	var lic []byte
 	var err error
-	switch filepath.Ext(path) {
+	switch fileExtension(path) {
 	default:
 		return nil
 	case ".c", ".h":
 		lic, err = prefix(tmpl, data, "/*", " * ", " */")
 	case ".js", ".jsx", ".tsx", ".css", ".tf":
 		lic, err = prefix(tmpl, data, "/**", " * ", " */")
-	case ".cc", ".cpp", ".cs", ".go", ".hh", ".hpp", ".java", ".m", ".mm", ".proto", ".rs", ".scala", ".swift", ".dart":
+	case ".cc", ".cpp", ".cs", ".go", ".hh", ".hpp", ".java", ".m", ".mm", ".proto", ".rs", ".scala", ".swift", ".dart", ".groovy":
 		lic, err = prefix(tmpl, data, "", "// ", "")
-	case ".py", ".sh", ".yaml", ".yml":
+	case ".py", ".sh", ".yaml", ".yml", ".dockerfile", "dockerfile", ".rb", "gemfile":
 		lic, err = prefix(tmpl, data, "", "# ", "")
 	case ".el", ".lisp":
 		lic, err = prefix(tmpl, data, "", ";; ", "")
@@ -178,10 +178,19 @@ func addLicense(path string, fmode os.FileMode, tmpl *template.Template, data *c
 	return ioutil.WriteFile(path, b, fmode)
 }
 
+func fileExtension(name string) string {
+	if v := filepath.Ext(name); v != "" {
+		return strings.ToLower(v)
+	}
+	return strings.ToLower(filepath.Base(name))
+}
+
 var head = []string{
-	"#!",        // shell script
-	"<?xml",     // XML declaratioon
-	"<!doctype", // HTML doctype
+	"#!",                       // shell script
+	"<?xml",                    // XML declaratioon
+	"<!doctype",                // HTML doctype
+	"# encoding:",              // Ruby encoding
+	"# frozen_string_literal:", // Ruby interpreter instruction
 }
 
 func hashBang(b []byte) []byte {
diff --git a/main_test.go b/main_test.go
index c2c0a67..41a95fa 100644
--- a/main_test.go
+++ b/main_test.go
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
@@ -53,7 +53,7 @@ func TestInitial(t *testing.T) {
 	for i := 0; i < 2; i++ {
 		t.Logf("run #%d", i)
 		targs := []string{"-test.run=TestInitial"}
-		cargs := []string{"-l", "apache", "-c", "Google Inc.", "-y", "2016", tmp}
+		cargs := []string{"-l", "apache", "-c", "Google LLC", "-y", "2018", tmp}
 		c := exec.Command(os.Args[0], append(targs, cargs...)...)
 		c.Env = []string{"RUNME=1"}
 		if out, err := c.CombinedOutput(); err != nil {
diff --git a/testdata/expected/Gemfile b/testdata/expected/Gemfile
new file mode 100644
index 0000000..1a245c7
--- /dev/null
+++ b/testdata/expected/Gemfile
@@ -0,0 +1,15 @@
+# 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.
+
+puts "Hello world!"
diff --git a/testdata/expected/file.Dockerfile b/testdata/expected/file.Dockerfile
new file mode 100644
index 0000000..a23d19e
--- /dev/null
+++ b/testdata/expected/file.Dockerfile
@@ -0,0 +1,16 @@
+# 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.
+
+FROM scratch
+CMD ["echo", "hello world"]
diff --git a/testdata/expected/file.c b/testdata/expected/file.c
index 7876b80..f5f0efd 100644
--- a/testdata/expected/file.c
+++ b/testdata/expected/file.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Google Inc.
+ * 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.
diff --git a/testdata/expected/file.cc b/testdata/expected/file.cc
index 53656ed..683ae6b 100644
--- a/testdata/expected/file.cc
+++ b/testdata/expected/file.cc
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.cpp b/testdata/expected/file.cpp
index 53656ed..683ae6b 100644
--- a/testdata/expected/file.cpp
+++ b/testdata/expected/file.cpp
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.cs b/testdata/expected/file.cs
index 8137f4f..b2700ef 100644
--- a/testdata/expected/file.cs
+++ b/testdata/expected/file.cs
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.css b/testdata/expected/file.css
index 8c01d2d..e0ecb5d 100644
--- a/testdata/expected/file.css
+++ b/testdata/expected/file.css
@@ -1,5 +1,5 @@
 /**
- * Copyright 2016 Google Inc.
+ * 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.
diff --git a/testdata/expected/file.dart b/testdata/expected/file.dart
index 8902b4a..e72661d 100644
--- a/testdata/expected/file.dart
+++ b/testdata/expected/file.dart
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.el b/testdata/expected/file.el
index aa2a060..ab301b8 100644
--- a/testdata/expected/file.el
+++ b/testdata/expected/file.el
@@ -1,4 +1,4 @@
-;; Copyright 2016 Google Inc.
+;; 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.
diff --git a/testdata/expected/file.erl b/testdata/expected/file.erl
index 190d223..fdebbaa 100644
--- a/testdata/expected/file.erl
+++ b/testdata/expected/file.erl
@@ -1,4 +1,4 @@
-% Copyright 2016 Google Inc.
+% 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.
diff --git a/testdata/expected/file.go b/testdata/expected/file.go
index 7efc920..6a3666a 100644
--- a/testdata/expected/file.go
+++ b/testdata/expected/file.go
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.groovy b/testdata/expected/file.groovy
new file mode 100644
index 0000000..fc86d5b
--- /dev/null
+++ b/testdata/expected/file.groovy
@@ -0,0 +1,17 @@
+// 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.
+
+def dummy_function() {
+    println "Hello world"
+}
diff --git a/testdata/expected/file.h b/testdata/expected/file.h
index fddab60..eacb361 100644
--- a/testdata/expected/file.h
+++ b/testdata/expected/file.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 Google Inc.
+ * 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.
diff --git a/testdata/expected/file.hh b/testdata/expected/file.hh
index 817dc30..a2bcb35 100644
--- a/testdata/expected/file.hh
+++ b/testdata/expected/file.hh
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.hpp b/testdata/expected/file.hpp
index 817dc30..a2bcb35 100644
--- a/testdata/expected/file.hpp
+++ b/testdata/expected/file.hpp
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.hs b/testdata/expected/file.hs
index 92f22dc..d2e1cb3 100644
--- a/testdata/expected/file.hs
+++ b/testdata/expected/file.hs
@@ -1,4 +1,4 @@
--- Copyright 2016 Google Inc.
+-- 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.
diff --git a/testdata/expected/file.html b/testdata/expected/file.html
index 0093653..25d75e7 100644
--- a/testdata/expected/file.html
+++ b/testdata/expected/file.html
@@ -1,6 +1,6 @@
 <!doctype html>
 <!--
- Copyright 2016 Google Inc.
+ 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.
diff --git a/testdata/expected/file.java b/testdata/expected/file.java
index 867a5df..f7bfa34 100644
--- a/testdata/expected/file.java
+++ b/testdata/expected/file.java
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.js b/testdata/expected/file.js
index 2d28b46..51b84be 100644
--- a/testdata/expected/file.js
+++ b/testdata/expected/file.js
@@ -1,5 +1,5 @@
 /**
- * Copyright 2016 Google Inc.
+ * 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.
diff --git a/testdata/expected/file.lisp b/testdata/expected/file.lisp
index 87368ea..71c3e53 100644
--- a/testdata/expected/file.lisp
+++ b/testdata/expected/file.lisp
@@ -1,4 +1,4 @@
-;; Copyright 2016 Google Inc.
+;; 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.
diff --git a/testdata/expected/file.m b/testdata/expected/file.m
index fb62e4c..9646b5c 100644
--- a/testdata/expected/file.m
+++ b/testdata/expected/file.m
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.mm b/testdata/expected/file.mm
index fb62e4c..9646b5c 100644
--- a/testdata/expected/file.mm
+++ b/testdata/expected/file.mm
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.php b/testdata/expected/file.php
index d19e850..9205707 100644
--- a/testdata/expected/file.php
+++ b/testdata/expected/file.php
@@ -1,5 +1,5 @@
 <?php
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.proto b/testdata/expected/file.proto
index 29614d8..3a68151 100644
--- a/testdata/expected/file.proto
+++ b/testdata/expected/file.proto
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.py b/testdata/expected/file.py
index 0dd9b5e..2413205 100644
--- a/testdata/expected/file.py
+++ b/testdata/expected/file.py
@@ -1,4 +1,4 @@
-# Copyright 2016 Google Inc.
+# 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.
diff --git a/testdata/expected/file.rb b/testdata/expected/file.rb
new file mode 100644
index 0000000..3f758cf
--- /dev/null
+++ b/testdata/expected/file.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+# 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.
+
+puts "Hello world!"
diff --git a/testdata/expected/file.rs b/testdata/expected/file.rs
index 662098a..38d5757 100644
--- a/testdata/expected/file.rs
+++ b/testdata/expected/file.rs
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.scala b/testdata/expected/file.scala
index 05971de..5b2d659 100644
--- a/testdata/expected/file.scala
+++ b/testdata/expected/file.scala
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.swift b/testdata/expected/file.swift
index 63243f0..0b58df8 100644
--- a/testdata/expected/file.swift
+++ b/testdata/expected/file.swift
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.
diff --git a/testdata/expected/file.tf b/testdata/expected/file.tf
index a6ce33e..29fa0ea 100644
--- a/testdata/expected/file.tf
+++ b/testdata/expected/file.tf
@@ -1,5 +1,5 @@
 /**
- * Copyright 2016 Google Inc.
+ * 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.
diff --git a/testdata/expected/file.xml b/testdata/expected/file.xml
index 425179f..4cbe42e 100644
--- a/testdata/expected/file.xml
+++ b/testdata/expected/file.xml
@@ -1,5 +1,5 @@
 <!--
- Copyright 2016 Google Inc.
+ 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.
diff --git a/testdata/expected/file1.sh b/testdata/expected/file1.sh
index 364f0ae..5ba7d9b 100644
--- a/testdata/expected/file1.sh
+++ b/testdata/expected/file1.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2016 Google Inc.
+# 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.
diff --git a/testdata/expected/file2.sh b/testdata/expected/file2.sh
index 93232fd..fe86eda 100644
--- a/testdata/expected/file2.sh
+++ b/testdata/expected/file2.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/go run prog.go $*
-# Copyright 2016 Google Inc.
+# 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.
diff --git a/testdata/expected/file2.xml b/testdata/expected/file2.xml
index ff225f8..9b18c0c 100644
--- a/testdata/expected/file2.xml
+++ b/testdata/expected/file2.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
 <!--
- Copyright 2016 Google Inc.
+ 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.
diff --git a/testdata/initial/Gemfile b/testdata/initial/Gemfile
new file mode 100644
index 0000000..08b85bf
--- /dev/null
+++ b/testdata/initial/Gemfile
@@ -0,0 +1 @@
+puts "Hello world!"
diff --git a/testdata/initial/file.Dockerfile b/testdata/initial/file.Dockerfile
new file mode 100644
index 0000000..eb8b2ad
--- /dev/null
+++ b/testdata/initial/file.Dockerfile
@@ -0,0 +1,2 @@
+FROM scratch
+CMD ["echo", "hello world"]
diff --git a/testdata/initial/file.groovy b/testdata/initial/file.groovy
new file mode 100644
index 0000000..3434ffa
--- /dev/null
+++ b/testdata/initial/file.groovy
@@ -0,0 +1,3 @@
+def dummy_function() {
+    println "Hello world"
+}
diff --git a/testdata/initial/file.rb b/testdata/initial/file.rb
new file mode 100644
index 0000000..de437c6
--- /dev/null
+++ b/testdata/initial/file.rb
@@ -0,0 +1,2 @@
+# frozen_string_literal: true
+puts "Hello world!"
diff --git a/tmpl.go b/tmpl.go
index 6ac2fbc..6efc831 100644
--- a/tmpl.go
+++ b/tmpl.go
@@ -1,4 +1,4 @@
-// Copyright 2016 Google Inc.
+// 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.