Compiler/CC3220SF-LAUNCHXL: Wrong mktime conversion

Tool/software: TI C/C++ Compiler

I set the internal RTC of CC3220SF to 1st January 2000, then I try to readback its value:

time_t GetEpoch(void)
{
    _i16 ret;
    _u8 pConfigOpt = SL_DEVICE_GENERAL_DATE_TIME;
    _u16 pConfigLen = sizeof(SlDateTime_t);

    SlDateTime_t dateTime = {0};
    ret = sl_DeviceGet(SL_DEVICE_GENERAL, &pConfigOpt, &pConfigLen, (unsigned char *) &dateTime);
    ASSERT_ON_ERROR(ret);

    struct tm t;
    time_t t_of_day;

    t.tm_year = dateTime.tm_year - 1900;
    t.tm_mon = dateTime.tm_mon - 1;
    t.tm_mday = dateTime.tm_day;
    t.tm_hour = dateTime.tm_hour;
    t.tm_min = dateTime.tm_min;
    t.tm_sec = dateTime.tm_sec;
    t.tm_isdst = -1;
    t_of_day = mktime(&t);

    UART_PRINT("SlDateTime_t: %d/%d/%d %d:%d:%d\r\n", dateTime.tm_year, dateTime.tm_mon, dateTime.tm_day, dateTime.tm_hour, dateTime.tm_min, dateTime.tm_sec);
    UART_PRINT("struct tm: %d/%d/%d %d:%d:%d\r\n", t.tm_year, t.tm_mon, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec);
    UART_PRINT("time_t   : %lld\r\n", t_of_day);

    return t_of_day;
}

Here the output:

SlDateTime_t: 2000/1/1 0:0:0                                              
struct tm: 100/0/1 0:0:0                                                  
time_t   : 2305849197122252192

Please note I'm using 64-bit time functions.

Both SlDateTime and tm structs are correct - why the time_t value is wrong? Is there any mistake in my code?