/* mktime uses local timezone */
*timestamp = tm_to_time_t(&tm);
- if (*offset == -1)
- *offset = ((time_t)*timestamp - mktime(&tm)) / 60;
+ if (*offset == -1) {
+ time_t temp_time = mktime(&tm);
+ if ((time_t)*timestamp > temp_time) {
+ *offset = ((time_t)*timestamp - temp_time) / 60;
+ } else {
+ *offset = -(int)((temp_time - (time_t)*timestamp) / 60);
+ }
+ }
if (*timestamp == -1)
return -1;