[tz] How to force zic output to TZIF?

Hi, I have a tz client that expects the tzdata in format TZIF (that's version \nul). It has become necessary to update the tzdata but it is not feasible to update the client. Is it possible with the current 2018d release to generate output in TZIF format (as opposed to TZIF2 or TZIF3)? If so, what needs to be modified? If not, what is the suggested approach? Thanks, Johan