diff -Naur busybox-1.13.3.orig/util-linux/umount.c busybox-1.13.3/util-linux/umount.c
--- busybox-1.13.3.orig/util-linux/umount.c	2009-02-26 12:47:43.000000000 +0100
+++ busybox-1.13.3/util-linux/umount.c	2009-06-04 02:31:59.000000000 +0200
@@ -39,7 +39,10 @@
 int umount_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int umount_main(int argc UNUSED_PARAM, char **argv)
 {
+#if defined(__linux__)
+	// from the comment above, doForce is highly Linux specific
 	int doForce;
+#endif
 	char *const path = xmalloc(PATH_MAX + 2); /* to save stack */
 	struct mntent me;
 	FILE *fp;
@@ -55,7 +58,9 @@
 	opt = getopt32(argv, OPTION_STRING, &fstype);
 	//argc -= optind;
 	argv += optind;
+#if defined(__linux__)
 	doForce = MAX((opt & OPT_FORCE), (opt & OPT_LAZY));
+#endif
 
 	/* Get a list of mount points from mtab.  We read them all in now mostly
 	 * for umount -a (so we don't have to worry about the list changing while
@@ -118,11 +123,17 @@
 		if (m) zapit = m->dir;
 
 		// Let's ask the thing nicely to unmount.
+#if defined(__FreeBSD_kernel__)
+		curstat = unmount(zapit, 0);
+#else
 		curstat = umount(zapit);
+#endif
 
+#if defined(__linux__)
 		// Force the unmount, if necessary.
 		if (curstat && doForce)
 			curstat = umount2(zapit, doForce);
+#endif
 
 		// If still can't umount, maybe remount read-only?
 		if (curstat) {
@@ -130,7 +141,11 @@
 				// Note! Even if we succeed here, later we should not
 				// free loop device or erase mtab entry!
 				const char *msg = "%s busy - remounted read-only";
+#if defined(__FreeBSD_kernel__)
+				curstat = verbose_mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
+#else
 				curstat = mount(m->device, zapit, NULL, MS_REMOUNT|MS_RDONLY, NULL);
+#endif
 				if (curstat) {
 					msg = "can't remount %s read-only";
 					status = EXIT_FAILURE;
@@ -138,7 +153,11 @@
 				bb_error_msg(msg, m->device);
 			} else {
 				status = EXIT_FAILURE;
+#if defined(__linux__)
 				bb_perror_msg("can't %sumount %s", (doForce ? "forcibly " : ""), zapit);
+#else
+				bb_perror_msg("can't %sumount %s", "", zapit);
+#endif
 			}
 		} else {
 			// De-allocate the loop device.  This ioctl should be ignored on