1 files changed, 11 insertions, 2 deletions

diff --git a/miscutils/mountpoint.c b/miscutils/mountpoint.c
index b541ce28c..a35c38907 100644
--- a/miscutils/mountpoint.c
+++ b/miscutils/mountpoint.c
@@ -55,8 +55,17 @@ int mountpoint_main(int argc UNUSED_PARAM, char **argv)
 
                         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) {
+                                const char *d = find_block_device(arg);
+                                /* name is undefined, but device is mounted -> anonymous superblock! */
+                                /* happens with btrfs */
+                                if (!d) {
+                                        d = "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;