--- extconf.rb~	2009-07-16 15:06:22.000000000 +0900
+++ extconf.rb	2009-07-16 15:06:25.000000000 +0900
@@ -24,5 +24,6 @@
 require 'mkmf'
 
 have_library("usb", "usb_init")
+have_header("ruby/st.h")
 
 create_makefile('usb')
--- usb.c~	2009-07-16 15:03:46.000000000 +0900
+++ usb.c	2009-07-16 15:04:53.000000000 +0900
@@ -19,7 +19,11 @@
 */
 
 #include "ruby.h"
+#ifdef HAVE_RUBY_ST_H
+#include "ruby/st.h"
+#else
 #include "st.h"
+#endif
 #include <usb.h>
 #include <errno.h>