-int _mach_snprintf(char *buffer, int length, const char *fmt, ...);
-int _mach_vsnprintf(char *buffer, int length, const char *fmt, va_list ap);
+int _mach_snprintf(char *buffer, int length, const char *fmt, ...) __printflike(3, 4);
+int _mach_vsnprintf(char *buffer, int length, const char *fmt, va_list ap) __printflike(3, 0);