Trivial-features ensures consistent *FEATURES* across multiple Common Lisp implementations.

For example, on MacOS X platforms, while most Lisps push `:DARWIN` to `*FEATURES*`, CLISP and Allegro push `:MACOS` and `:MACOSX` instead, respectively. Some Lisps might not push any feature suggesting MacOS X at all. trivial-features will make sure all Lisps will have `:DARWIN` in the `*FEATURES*` list when running on MacOS X. This way, you can write

#+darwin foo #-darwin bar

instead of

#+(or darwin macos macosx) foo #-(or darwin macos macosx) bar