diff --git a/src/basic/blockdev-util.c b/src/basic/blockdev-util.c
index b15b8cf770..6495a71658 100644
--- a/src/basic/blockdev-util.c
+++ b/src/basic/blockdev-util.c
@@ -81,6 +81,7 @@ int get_block_device(const char *path, dev_t *dev) {
         if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
                 return btrfs_get_block_device(path, dev);
 
+        *dev = 0;
         return 0;
 }
 
diff --git a/src/basic/btrfs-util.c b/src/basic/btrfs-util.c
index 7720d98009..32a022f7ce 100644
--- a/src/basic/btrfs-util.c
+++ b/src/basic/btrfs-util.c
@@ -277,8 +277,10 @@ int btrfs_get_block_device_fd(int fd, dev_t *dev) {
                 return -errno;
 
         /* We won't do this for btrfs RAID */
-        if (fsi.num_devices != 1)
+        if (fsi.num_devices != 1) {
+                *dev = 0;
                 return 0;
+        }
 
         for (id = 1; id <= fsi.max_id; id++) {
                 struct btrfs_ioctl_dev_info_args di = {