diff --git a/LICENSE.rdoc b/LICENSE.rdoc
index c61bb93398..24ddfd2d82 100644
--- a/LICENSE.rdoc
+++ b/LICENSE.rdoc
@@ -1,9 +1,10 @@
+# SPDX-License-Identifier: Ruby
+
 = License
 
 RDoc is copyrighted free software.
 
-You can redistribute it and/or modify it under either the terms of the GPL
-version 2 (see the file GPL), or the conditions below:
+You can redistribute it and/or modify it under the terms of the Ruby License.
 
 1. You may make and give away verbatim copies of the source form of the
    software without restriction, provided that you duplicate all of the
diff --git a/lib/rdoc/rd.rb b/lib/rdoc/rd.rb
index 0afbb26d35..d517a238a1 100644
--- a/lib/rdoc/rd.rb
+++ b/lib/rdoc/rd.rb
@@ -14,7 +14,7 @@
 # You can find the original source for rdtool at
 # https://github.com/uwabami/rdtool/
 #
-# You can use, re-distribute or change these files under Ruby's License or GPL.
+# You can use, re-distribute or change these files under Ruby's License.
 #
 # 1. You may make and give away verbatim copies of the source form of the
 #    software without restriction, provided that you duplicate all of the