diff --git a/tools/dev/header.txt b/tools/dev/header.txt
index 79e6e7f..f19f002 100644
--- a/tools/dev/header.txt
+++ b/tools/dev/header.txt
@@ -1,4 +1,4 @@
-Copyright $today.year-present Open Networking Laboratory
+Copyright ${today.year}-present Open Networking Laboratory
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.