diff --git a/include/bootflow.h b/include/bootflow.h
index ed9b61f..735ed87 100644
--- a/include/bootflow.h
+++ b/include/bootflow.h
@@ -43,7 +43,7 @@
  * @glob_node: Points to siblings in the global list (all bootdev)
  * @dev: Bootdevice device which produced this bootflow
  * @blk: Block device which contains this bootflow, NULL if this is a network
- *	device
+ *	device or sandbox 'host' device
  * @part: Partition number (0 for whole device)
  * @fs_type: Filesystem type (FS_TYPE...) if this is fixed by the media, else 0.
  *	For example, the sandbox host-filesystem bootdev sets this to
diff --git a/include/bootmeth.h b/include/bootmeth.h
index 669b14c..bdce301 100644
--- a/include/bootmeth.h
+++ b/include/bootmeth.h
@@ -240,7 +240,7 @@
  * caller before reading the file.
  *
  * @bflow: Information about file to try
- * @desc: Block descriptor to read from
+ * @desc: Block descriptor to read from (NULL for sandbox host)
  * @prefix: Filename prefix to prepend to @fname (NULL for none)
  * @fname: Filename to read
  * Return: 0 if OK, -ENOMEM if not enough memory to allocate bflow->fname,