diff --git a/src/libvirt-storage.c b/src/libvirt-storage.c
index cebe02fdda..48996ba4c9 100644
--- a/src/libvirt-storage.c
+++ b/src/libvirt-storage.c
@@ -1725,11 +1725,16 @@ virStorageVolDelete(virStorageVolPtr vol,
  * @vol: pointer to storage volume
  * @flags: extra flags; not used yet, so callers should always pass 0
  *
- * Ensure data previously on a volume is not accessible to future
- * reads. Also note, that depending on the actual volume
- * representation, this call may not really overwrite the
- * physical location of the volume. For instance, files stored
- * journaled, log structured, copy-on-write, versioned, and
+ * Ensure data previously on a volume is not accessible to future reads.
+ *
+ * The data to be wiped may include the format and possibly size information,
+ * so non-raw images might become raw with a different size. It is storage
+ * backend dependent whether the format and size information is regenerated
+ * once the initial volume wipe is completed.
+ *
+ * Depending on the actual volume representation, this call may not
+ * overwrite the physical location of the volume. For instance, files
+ * stored journaled, log structured, copy-on-write, versioned, and
  * network file systems are known to be problematic.
  *
  * Returns 0 on success, or -1 on error