diff --git a/ChangeLog b/ChangeLog
index 49d2292b30..e687418c2b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jan 13 18:19:49 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* io.c (rb_io_initialize): workaround for Windows. [ruby-dev:37686]
+          (also see [ruby-dev:37721])
+
 Tue Jan 13 17:29:02 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* enc/trans/make_transdb.rb (converters): should not depend on the
diff --git a/io.c b/io.c
index 46136d7ee7..5e50b0981d 100644
--- a/io.c
+++ b/io.c
@@ -5963,6 +5963,12 @@ rb_io_initialize(int argc, VALUE *argv, VALUE io)
     fp->encs = convconfig;
     clear_codeconv(fp);
     io_check_tty(fp);
+    if (fileno(stdin) == fd)
+	fp->stdio_file = stdin;
+    else if (fileno(stdout) == fd)
+	fp->stdio_file = stdout;
+    else if (fileno(stderr) == fd)
+	fp->stdio_file = stderr;
 
     return io;
 }