how to overcome underscore in A record

[PM Wong]

We've been using the older version (pre 9.3) 
and the underscore in the hostname in A recored
like
this_machine IN A 123.2.234.4

is okay.
We have to upgrade the bind to 9.5
The new version does not like underscore in the hostname

Is there any way to workaround ?
(otherwise we have to re-publish the web site URL
with a new one 
as the user has used the underscore in its web site
for quite some time)