diff -Naur busybox.orig/util-linux/rdev.c busybox/util-linux/rdev.c
--- busybox.orig/util-linux/rdev.c	2008-09-04 19:44:23 +0000
+++ busybox/util-linux/rdev.c	2008-09-17 12:38:57 +0000
@@ -12,12 +12,13 @@
 #include "libbb.h"
 
 int rdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int rdev_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
+int rdev_main(int argc UNUSED_PARAM, char **argv)
 {
-	char const * const root_device = find_block_device("/");
+	const char *dir = (argv[1]) ? argv[1] : "/";
+	char const * const root_device = find_block_device(dir);
 
 	if (root_device != NULL) {
-		printf("%s /\n", root_device);
+		printf("%s %s\n", root_device, dir);
 		return EXIT_SUCCESS;
 	}
 	return EXIT_FAILURE;