diff --git a/usr.sbin/mountd/mountd.c b/usr.sbin/mountd/mountd.c
--- a/usr.sbin/mountd/mountd.c
+++ b/usr.sbin/mountd/mountd.c
@@ -130,10 +130,11 @@
 	SLIST_ENTRY(exportlist) entries;
 };
 /* ex_flag bits */
-#define	EX_LINKED	0x1
-#define	EX_DONE		0x2
-#define	EX_DEFSET	0x4
-#define	EX_PUBLICFH	0x8
+#define	EX_LINKED	0x01
+#define	EX_DONE		0x02
+#define	EX_DEFSET	0x04
+#define	EX_PUBLICFH	0x08
+#define	EX_ADMINWARN	0x10
 
 SLIST_HEAD(exportlisthead, exportlist);
 
@@ -272,6 +273,7 @@
 static char **exnames;
 static char **hosts = NULL;
 static int force_v2 = 0;
+static int warn_admin = 1;
 static int resvport_only = 1;
 static int nhosts = 0;
 static int dir_only = 1;
@@ -434,11 +436,14 @@
 	else
 		close(s);
 
-	while ((c = getopt(argc, argv, "2deh:lnp:RrS")) != -1)
+	while ((c = getopt(argc, argv, "2Adeh:lnp:RrS")) != -1)
 		switch (c) {
 		case '2':
 			force_v2 = 1;
 			break;
+		case 'A':
+			warn_admin = 0;
+			break;
 		case 'e':
 			/* now a no-op, since this is the default */
 			break;
@@ -1696,6 +1701,20 @@
 						fsb.f_fsid.val[1]);
 				    }
 
+				    if (warn_admin != 0 &&
+					(ep->ex_flag & EX_ADMINWARN) == 0 &&
+					strcmp(unvis_dir, fsb.f_mntonname) !=
+					0) {
+					if (debug)
+					    warnx("exporting %s exports entire "
+						"%s file system", unvis_dir,
+						    fsb.f_mntonname);
+					syslog(LOG_ERR, "Warning: exporting %s "
+					    "exports entire %s file system",
+					    unvis_dir, fsb.f_mntonname);
+					ep->ex_flag |= EX_ADMINWARN;
+				    }
+
 				    /*
 				     * Add dirpath to export mount point.
 				     */