I'm unable to duplicate the problem. --ado Script started on Thu May 13 03:49:04 1999 gertrude$ cat mktimetest.c #include <stdio.h> #include <time.h> #include <errno.h> int main() { struct tm tm; time_t secs; memset(&tm, 0, sizeof tm); tm.tm_year = 99; tm.tm_mon = 4; tm.tm_mday = 13; secs = mktime(&tm); printf("secs: %ld\n", secs); if (secs < 0) printf("strerror(errno): %s\n", strerror(errno)); return 0; } gertrude$ cc mktimetest.c libtz.a -o mktimetest gertrude$ TZ=Europe/Paris ./mktimetest secs: 926550000 gertrude$ TZ=America/New_York ./mktimetest secs: 926571600 gertrude$ TZ=CET-1CEST-2 ./mktimetest secs: 926550000 gertrude$ exit script done on Thu May 13 03:50:23 1999