diff --git a/usr.bin/su/su.1 b/usr.bin/su/su.1
index a5e25e669da0..78ce5f15bd1b 100644
--- a/usr.bin/su/su.1
+++ b/usr.bin/su/su.1
@@ -30,7 +30,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	@(#)su.1	8.2 (Berkeley) 4/18/94
-.\"	$Id: su.1,v 1.13 1998/05/25 03:34:52 steve Exp $
+.\"	$Id: su.1,v 1.14 1998/06/08 05:29:51 jkoshy Exp $
 .\"
 .\" this is for hilit19's braindeadness: "
 .Dd April 18, 1994
@@ -161,6 +161,11 @@ By default (unless the prompt is reset by a startup file) the super-user
 prompt is set to
 .Dq Sy \&#
 to remind one of its awesome power.
+.Sh FILES
+.Bl -tag -width /etc/auth.conf -compact
+.It Pa /etc/auth.conf
+configure authentication services
+.El
 .Sh SEE ALSO
 .Xr csh 1 ,
 .Xr kerberos 1 ,
diff --git a/usr.bin/su/su.c b/usr.bin/su/su.c
index f2196a020a93..9fdc9e7b16ea 100644
--- a/usr.bin/su/su.c
+++ b/usr.bin/su/su.c
@@ -42,7 +42,7 @@ static const char copyright[] =
 static char sccsid[] = "@(#)su.c	8.3 (Berkeley) 4/2/94";
 #endif
 static const char rcsid[] =
-	"$Id: su.c,v 1.27 1998/05/26 06:39:08 danny Exp $";
+	"$Id: su.c,v 1.28 1998/09/21 07:44:25 roberto Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -59,6 +59,7 @@ static const char rcsid[] =
 #include <string.h>
 #include <syslog.h>
 #include <unistd.h>
+#include <libutil.h>
 
 #ifdef LOGIN_CAP
 #include <login_cap.h>
@@ -185,6 +186,11 @@ main(argc, argv)
 
 	argv += optind;
 
+#ifdef KERBEROS
+	k = auth_getval("auth_list");
+	if (k && !strstr(k, "kerberos"))
+	    use_kerberos = 0;
+#endif
 	errno = 0;
 	prio = getpriority(PRIO_PROCESS, 0);
 	if (errno)