AC_CHECK_HEADERS(security/pam_modules.h siad.h usersec.h ucontext.h)
AC_CHECK_FUNCS(utimes random srandom getdtablesize snprintf re_comp re_exec)
-AC_CHECK_FUNCS(setprogname getprogname sigaction mkstemp)
+AC_CHECK_FUNCS(setprogname getprogname sigaction mkstemp vsnprintf)
AC_CHECK_TYPE(ssize_t, int)
AC_SIZEOF_TYPE(long)