diff --git a/include/ruby/backward/rubyio.h b/include/ruby/backward/rubyio.h
deleted file mode 100644
index 433f425988..0000000000
--- a/include/ruby/backward/rubyio.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef RUBY_BACKWARD_RUBYIO_H                       /*-*-C++-*-vi:se ft=cpp:*/
-#define RUBY_BACKWARD_RUBYIO_H
-/**
- * @file
- * @author     Ruby developers <ruby-core@ruby-lang.org>
- * @copyright  This  file  is   a  part  of  the   programming  language  Ruby.
- *             Permission  is hereby  granted,  to  either redistribute  and/or
- *             modify this file, provided that  the conditions mentioned in the
- *             file COPYING are met.  Consult the file for details.
- */
-#if   defined __GNUC__
-#warning use "ruby/io.h" instead of "rubyio.h"
-#elif defined _MSC_VER
-#pragma message("warning: use \"ruby/io.h\" instead of \"rubyio.h\"")
-#endif
-#include "ruby/io.h"
-
-#endif /* RUBY_BACKWARD_RUBYIO_H */