<http://savannah.gnu.org/bugs/?22017> reports an interesting test case whereby zic generates data that crashes the Linux kernel. I thought I'd forward it to this mailing list so that non-Linux people can hear about it. Here's the test case. It makes the GNU C library tzfile.c fail with an assertion that numtypes==1. # /etc/timezone (auto-generated) # Daylight savings time rules # Name YrStart YrEnd Type Month,Day,At,Offset Letter Rule DAYLIGHT 2000 max - Mar lastSun 02:00 01:00 - Rule DAYLIGHT 2000 max - Oct lastSun 03:00 -01:00 - # Timezone description # NAME Offset Rule Name(/DaylightName) Zone localtime 00:00 DAYLIGHT GMT/BST