Update copyright date.
diff --git a/etree_test.go b/etree_test.go
index 92927d6..bf2f6f5 100644
--- a/etree_test.go
+++ b/etree_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 Brett Vickers.
+// Copyright 2015-2019 Brett Vickers.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/example_test.go b/example_test.go
index bdfdf23..02f5976 100644
--- a/example_test.go
+++ b/example_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 Brett Vickers.
+// Copyright 2015-2019 Brett Vickers.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/helpers.go b/helpers.go
index 069c3c2..825e14e 100644
--- a/helpers.go
+++ b/helpers.go
@@ -1,4 +1,4 @@
-// Copyright 2015 Brett Vickers.
+// Copyright 2015-2019 Brett Vickers.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/path_test.go b/path_test.go
index 1e0b972..d94968a 100644
--- a/path_test.go
+++ b/path_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 Brett Vickers.
+// Copyright 2015-2019 Brett Vickers.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.