Stop makepkg from running gpg on .sig files

Hello, apparently makepkg automatically attempts to verify .sig files in the SOURCES array with gpg. Can I somehow stop this behaviour? I have .sig URLs but these aren't GPG signatures, but SSH signatures I'd like to validate in a custom verify() function. Currently, I'm working around this by renaming the upstream .sig files to .sigssh in SOURCES, but that's rather inconvenient. Cheers, Basti