Index: uspace/srv/vfs/vfs_ops.c
===================================================================
--- uspace/srv/vfs/vfs_ops.c	(revision f2ec8c8a9370e04756e68eab848a456f0374de5f)
+++ uspace/srv/vfs/vfs_ops.c	(revision 2f60a5290eb6b781b8644febd27bc3c984f97c1b)
@@ -189,4 +189,13 @@
 		/* We already have the root FS. */
 		rwlock_write_lock(&namespace_rwlock);
+		if ((size == 1) && (buf[0] == '/')) {
+			/* Trying to mount root FS over root FS */
+			rwlock_write_unlock(&namespace_rwlock);
+			futex_up(&rootfs_futex);
+			vfs_node_put(mr_node);
+			free(buf);
+			ipc_answer_0(rid, EBUSY);
+			return;
+		}
 		rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
 		if (rc != EOK) {