diff --git a/lib/Simba/CA.pm b/lib/Simba/CA.pm
index 420aeee..4000da3 100644
--- a/lib/Simba/CA.pm
+++ b/lib/Simba/CA.pm
@@ -663,9 +663,11 @@ sub store_file {
         my $file_bfd;
         unless (open($file_bfd, '>:raw', $backup_filename)) {
             $self->log(5, "cannot open backup file $backup_filename: $!");
-            # There may be some errors from which we can recover, e.g., for 
+            # XXX - There may be some errors from which we can recover, e.g., for 
             # "File name too long" we could just shorten the file name. But for
             # now we just skip the file:
+            # XXX - some other errors are almost certainly fatal, e.g., ENOENT
+            # probably means that our backup device has been unmounted (BTDT).
             $self->close_file_connection;
             return 0;
         }