diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c
index 8281dc76a..267dea263 100644
--- a/lib/device/dev-io.c
+++ b/lib/device/dev-io.c
@@ -42,7 +42,7 @@ int dev_get_size(struct device *dev, uint64_t *size)
 		return 0;
 	}
 
-	*size >>= BLKSIZE_SHIFT;
+	*size >>= BLKSIZE_SHIFT;	/* Convert to sectors */
 	close(fd);
 	return 1;
 }