Free 0-level spells in spellbook of custom class

[Redcap's Corner]

I have a file I put together for a custom class that casts from spellbooks. I had no problems getting the starting spellbook working for the class, complete with free cantrips. I left the "Free Initial Spells in Spellbook" and "Free Spells/Level" fields blank, so they would default to 3+Int and 2, respectively, and they are, but they're counting the cantrips against those limits. Right now I only have 6 cantrips loaded in the spellbook (two of which are from the core rulebook, and four of which are custom cantrips). With a starting Int of 12, I should get 4 free spells at 1st level, but before I add any 1st-level spells, Hero Lab tells me I'm 2 spells over my free spell limit. I've looked at other spellbook-based classes and it doesn't look like I'm doing anything relevantly different on either the class or the starting spellbook, but magi and wizards don't seem to have this issue. What can I do to avoid it for my class?