gpg – pinentry-mac: disable Keychain storage

I’m using pinentry-mac with openfortivpn, to prompt for passwords and tokens. I installed both using Homebrew.

However, there’s a button in the pinentry dialog to save to the keychain, and it’s checked by default. I’d like to disable this, or at least make it unchecked by default.

Based on this and this and the source, I’ve tried both of these:

defaults write org.gpgtools.common DisableKeychain -bool yes
defaults write org.gpgtools.common UseKeychain false

But neither had any effect. Anything else I can do?