diff --git a/sbin/mdconfig/mdconfig.8 b/sbin/mdconfig/mdconfig.8
index 3de3af8d0bb7..0f993575aa1e 100644
--- a/sbin/mdconfig/mdconfig.8
+++ b/sbin/mdconfig/mdconfig.8
@@ -101,7 +101,11 @@ becomes the backingstore for this memory disk.
 Swap space is used to back this memory disk.
 .El
 .It Fl f Ar file
-Filename to use for the vnode type memory disk.
+Filename to use for the vnode type memory disk. Options
+.Fl a
+and
+.Fl t Ar vnode
+are implied if not specified.
 .It Fl l
 List configured devices.
 If given with
@@ -118,7 +122,11 @@ is the number of 512 byte sectors unless suffixed with a
 or
 .Cm t
 which
-denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
+denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. Options
+.Fl a
+and
+.Fl t Ar malloc
+are implied if not specified.
 .It Fl S Ar sectorsize
 Sectorsize to use for malloc backed device.
 .It Fl x Ar sectors/track
diff --git a/sbin/mdconfig/mdconfig.c b/sbin/mdconfig/mdconfig.c
index 4fc580c115f8..068aaba64a0a 100644
--- a/sbin/mdconfig/mdconfig.c
+++ b/sbin/mdconfig/mdconfig.c
@@ -130,8 +130,6 @@ main(int argc, char **argv)
 			cmdline=2;
 			break;
 		case 'f':
-			if (cmdline != 0 && cmdline != 1 && cmdline != 2)
-				usage();
 			if (cmdline == 0) {
 				action = ATTACH;
 				cmdline = 1;
@@ -142,6 +140,8 @@ main(int argc, char **argv)
 				mdio.md_options = MD_CLUSTER | MD_AUTOUNIT | MD_COMPRESS;
 				cmdline = 2;
 			}
+ 			if (cmdline != 2)
+ 				usage();
 			if (realpath(optarg, mdio.md_file) == NULL) {
 				err(1, "could not find full path for %s",
 				    optarg);
@@ -194,6 +194,17 @@ main(int argc, char **argv)
 			mdio.md_sectorsize = strtoul(optarg, &p, 0);
 			break;
 		case 's':
+			if (cmdline == 0) {
+				/* Imply ``-a'' */
+				action = ATTACH;
+				cmdline = 1;
+			}
+			if (cmdline == 1) {
+				/* Imply ``-t malloc'' */
+				mdio.md_type = MD_MALLOC;
+				mdio.md_options = MD_AUTOUNIT | MD_COMPRESS;
+				cmdline = 2;
+			}
 			if (cmdline != 2)
 				usage();
 			mdio.md_mediasize = (off_t)strtoumax(optarg, &p, 0);