diff --git a/include/common.h b/include/common.h
index 940161f..5c952af 100644
--- a/include/common.h
+++ b/include/common.h
@@ -359,6 +359,7 @@
 void	serial_puts   (const char *);
 int	serial_getc   (void);
 int	serial_tstc   (void);
+int	serial_setconfig(uint config);
 
 /* $(CPU)/speed.c */
 int	get_clocks (void);