diff --git a/gtsam/base/std_optional_serialization.h b/gtsam/base/std_optional_serialization.h
index d4ed4f53d..051b84908 100644
--- a/gtsam/base/std_optional_serialization.h
+++ b/gtsam/base/std_optional_serialization.h
@@ -1,6 +1,13 @@
-// Functionality to serialize std::optional<T> to boost::archive
-// Following this:
-// PR: https://github.com/boostorg/serialization/pull/148/files#
+/* ----------------------------------------------------------------------------
+* Use, modification and distribution is subject to the Boost Software
+* License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+* http://www.boost.org/LICENSE_1_0.txt)
+
+* See http://www.boost.org for updates, documentation, and revision history.
+
+* Functionality to serialize std::optional<T> to boost::archive
+* Inspired from this PR: https://github.com/boostorg/serialization/pull/163
+* ---------------------------------------------------------------------------- */
 
 #pragma once
 #include <optional>