diff --git a/ChangeLog b/ChangeLog
index 4406d73e07..04c6564b58 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,6 @@
-Tue Jun 10 11:24:43 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Tue Jun 10 11:25:15 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ruby.c (rb_argv0): revised for ext/tk.
 
 	* include/ruby/encoding.h: not to use varargs.h since requiring C89.
 
diff --git a/ruby.c b/ruby.c
index a8945ea0d7..bf80c95273 100644
--- a/ruby.c
+++ b/ruby.c
@@ -955,6 +955,7 @@ opt_enc_index(VALUE enc_name)
 }
 
 #define rb_progname (GET_VM()->progname)
+VALUE rb_argv0;
 
 static VALUE
 process_options(VALUE arg)
@@ -1470,6 +1471,7 @@ ruby_prog_init(void)
     rb_define_hooked_variable("$PROGRAM_NAME", &rb_progname, 0, set_arg0);
 
     rb_define_global_const("ARGV", rb_argv);
+    rb_global_variable(&rb_argv0);
 
 #ifdef MSDOS
     /*
@@ -1525,6 +1527,7 @@ ruby_process_options(int argc, char **argv)
     NODE *tree;
 
     ruby_script(argv[0]);	/* for the time being */
+    rb_argv0 = rb_str_new4(rb_progname);
     args.argc = argc;
     args.argv = argv;
     args.opt = cmdline_options_init(&opt);