Composer getting old

I just wanted to update some dependencies, but ran into this thing:

Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"

Turned out the composer version was really old. I tried to run a self-update, but that wouldn't work either for the same reason.

When you run into this message, a full re-install through https://getcomposer.org/download/ might do the trick. After I got the new version up and running, all messages were gone.