Pursuant to Michal's comment at https://puszcza.gnu.org.ua/bugs/?217.
1) I'm afraid I don't really understand tex4ht file derivation, despite Deimi's best efforts to explain. 2) Nevertheless, by grepping the logs, I see that nearly everything depends on mktex4ht.4ht and tex4ht.sty. I just added those as common dependencies (except for the files which generate them). Hope it helps and doesn't break anything. Easy enough to revert/tweak, of course. I admit I'm doubtful that the particular case Michal writes about (adding a new html4-related entry to mktex4ht-cnf.tex) is completely addressed. 3) It sure would be nice to have complete auto-generated dependencies, as we were discussing some time ago. Maybe someday ... Now, must get back to another neglected task :( ... -k