--- Rakefile~	2021-03-17 23:49:38.000000000 +0000
+++ Rakefile	2021-10-06 18:35:20.948000000 +0000
@@ -19,7 +19,7 @@ begin
 
   class RDoc::RDoc
 
-    alias old_parse_files parse_files
+    alias_method :old_parse_files, :parse_files if !instance_methods.include?(:old_parse_files)
 
     def parse_files(options)
       file_info = old_parse_files(options)