-AC_CHECK_MEMBERS(struct utmp.ut_type,,,[#include <utmp.h>])
+dnl For platforms such as FreeBSD that have tm_gmtoff in struct tm.
+dnl (FreeBSD has a timezone() function but not a timezone global
+dnl variable that is visible).
+AC_CHECK_MEMBERS([struct tm.tm_gmtoff],,,[#include <time.h>])