--- busybox.orig/miscutils/mountpoint.c	Tue May  5 17:03:35 2009
+++ busybox/miscutils/mountpoint.c	Mon Oct 26 11:24:50 2009
@@ -55,8 +55,17 @@
 
 			if (opt & OPT_d)
 				printf("%u:%u\n", major(st_dev), minor(st_dev));
-			if (opt & OPT_n)
-				printf("%s %s\n", find_block_device(arg), arg);
+			if (opt & OPT_n) {
+				// get the name of mounted block device
+				char *d = find_block_device(arg);
+				// name is undefined, but device is mounted -> anonymous superblock!
+				if (NULL == d) {
+					d = (char *)"UNKNOWN";
+					// TODO: iterate /proc/mounts, or /proc/self/mountinfo
+					// to find out the device name
+				}
+				printf("%s %s\n", d, arg);
+			}
 			if (!(opt & (OPT_q | OPT_d | OPT_n)))
 				printf("%s is %sa mountpoint\n", arg, is_not_mnt ? "not " : "");
 			return is_not_mnt;