requireHeader Pipeline Helper Returning Http 404

[scorelocity]

I'm using the requireHeader pipeline helper in Program.fs in the following way:

let headerPipe = pipeline {
   plug (requireHeader apiKeyName apiKeyValue) // where apiKeyName and apiKeyValue are retrieved from environment varialbes
}

let app = application {
   pipe_through headerPipe
.
.
.
}

This returns an http 404 Not Found when the correct header is not provided in the request. Is there a way to change this to return http 401 Unauthorized? Is there a better way in Saturn to require a particular api key in a header?

If this is more appropriately asked in Discussions, I'd be happy to move it there.