diff --git a/configure.in b/configure.in
index bc47b3494..37ccfda2a 100644
--- a/configure.in
+++ b/configure.in
@@ -246,10 +246,11 @@ dnl Checks for library functions.
 AC_BROKEN_SNPRINTF
 AC_BROKEN_VSNPRINTF
 
-AC_CHECK_FUNCS(_getpty _scrsize asnprintf asprintf fcntl gethostname getlogin)
+AC_CHECK_FUNCS(_getpty _scrsize asnprintf asprintf dn_expand fcntl)
+AC_CHECK_FUNCS(gethostname getlogin)
 AC_CHECK_FUNCS(getmsg getrlimit getspnam getspuid gettimeofday getuid)
 AC_CHECK_FUNCS(grantpt logwtmp mktime ptsname rand random)
-AC_CHECK_FUNCS(revoke select setitimer setlogin setpcred setpgid)
+AC_CHECK_FUNCS(revoke res_search select setitimer setlogin setpcred setpgid)
 AC_CHECK_FUNCS(setregid setresgid setresuid setreuid setutent)
 AC_CHECK_FUNCS(setsid setsockopt sigaction strstr)
 AC_CHECK_FUNCS(sysconf sysctl timegm ttyname ttyslot umask uname)