+#ifdef __GNUC__
+void prom_vprintf (char *fmt, va_list ap) __attribute__ ((format (printf, 1, 0)));
+void prom_fprintf (prom_handle dev, char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
+void prom_printf (char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+#else