-void xsb_broadcast(const char *command, server *service, const char *format, ...);
-void xsb_unicast(const char *command, nick *np, const char *format, ...);
+void xsb_broadcast(const char *command, server *service, const char *format, ...) __attribute__ ((format (printf, 3, 4)));
+void xsb_unicast(const char *command, nick *np, const char *format, ...) __attribute__ ((format (printf, 3, 4)));