diff --git a/usr.sbin/boot0cfg/boot0cfg.8 b/usr.sbin/boot0cfg/boot0cfg.8
index e949cc76c249..bb73d753d058 100644
--- a/usr.sbin/boot0cfg/boot0cfg.8
+++ b/usr.sbin/boot0cfg/boot0cfg.8
@@ -22,7 +22,7 @@
 .\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 .\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\"	$Id: boot0cfg.8,v 1.1.1.1 1999/02/21 21:23:42 rnordier Exp $
+.\"	$Id: boot0cfg.8,v 1.2 1999/02/22 09:36:54 rnordier Exp $
 .\"
 .Dd February 21, 1999
 .Dt BOOT0CFG 8
@@ -101,7 +101,7 @@ the conventional (CHS) interface, when accessing disk-related BIOS
 services.  The default is
 .Sq nopacket .
 .It setdrv
-Causes the drive containing the disk to be referenced using drive
+Forces the drive containing the disk to be referenced using drive
 number definable by means of the -d option.  The default is
 .Sq nosetdrv .
 .It update
@@ -131,7 +131,7 @@ option may cause
 .Sq boot0
 to fail, depending on the nature of BIOS support.
 .Pp
-The
+Use of the
 .Sq setdrv
-option is presently implemented
-.Dq syntactically but not semantically .
+option with an incorrect -d operand may cause the MBR to be written
+to the wrong disk.  Be careful!
diff --git a/usr.sbin/boot0cfg/boot0cfg.c b/usr.sbin/boot0cfg/boot0cfg.c
index 67d0c882d216..20fdcc34e90c 100644
--- a/usr.sbin/boot0cfg/boot0cfg.c
+++ b/usr.sbin/boot0cfg/boot0cfg.c
@@ -26,7 +26,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-	"$Id: boot0cfg.c,v 1.1.1.1 1999/02/21 21:23:42 rnordier Exp $";
+	"$Id: boot0cfg.c,v 1.2 1999/02/22 09:36:54 rnordier Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -44,6 +44,7 @@ static const char rcsid[] =
 
 #define MBRSIZE         512     /* master boot record size */
 
+#define OFF_DRIVE	0x1ba	/* offset: setdrv drive */
 #define OFF_FLAGS       0x1bb   /* offset: option flags */
 #define OFF_TICKS       0x1bc   /* offset: clock ticks */
 #define OFF_PTBL        0x1be   /* offset: partition table */
@@ -154,6 +155,8 @@ main(int argc, char *argv[])
             errx(1, "%s: bad magic", bpath);
         memcpy(buf + OFF_PTBL, part, sizeof(part));
     }
+    if (d_arg != -1)
+	buf[OFF_DRIVE] = d_arg;
     if (o_flag) {
         buf[OFF_FLAGS] &= o_and;
         buf[OFF_FLAGS] |= o_or;
@@ -185,7 +188,7 @@ main(int argc, char *argv[])
                        part[i].dp_size);
             }
         printf("\n");
-        printf("drive=0x0  options=");
+        printf("drive=0x%x  options=", buf[OFF_DRIVE]);
         for (i = 0; i < nopt; i++) {
             if (i)
                 printf(",");