snprintf (printf) 64 bit integer uint64_t

We fail to use snprintf() with typical printf-formatter to create hex or decimal strings from uint64_t values.

    uint64_t a = 0x1122334455667788L;
    snprintf( buf, 20, "%x", a); // => 11223344
    snprintf( buf, 20, "%lx", a); // => 11223344
    snprintf( buf, 20, "%llu", a); // => lu
    snprintf( buf, 20, "%llx", a); // lx

Any ideas?