diff --git a/ChangeLog b/ChangeLog
index 14a6952ace..7898cf2b4d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Dec 15 11:35:27 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm.c (vm_backtrace): defaults to script name for C functions.
+
 Mon Dec 15 11:32:18 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (rubylib_mangled_path, rubylib_mangled_path2): cannot use
diff --git a/vm.c b/vm.c
index 6c06a21c09..f91f3586e2 100644
--- a/vm.c
+++ b/vm.c
@@ -704,7 +704,7 @@ vm_backtrace(rb_thread_t *th, int lev)
     }
 
     ary = vm_backtrace_each(th, RUBY_VM_NEXT_CONTROL_FRAME(cfp),
-			    top_of_cfp, "", 0, ary);
+			    top_of_cfp, RSTRING_PTR(th->vm->progname), 0, ary);
     return ary;
 }