Logging the response

[precisemath]

I am trying to log the status code of every response like this:

let customResponseLogger =
        fun (nxt: HttpFunc) (ctx: HttpContext)->
            let logger = ctx.Items["CustomILogger"] :?> ILogger
            logger.LogInformation (ctx.Response.StatusCode.ToString())
            nxt ctx

let secureRouter = router {
    pipe_through (Auth.requireAuthentication JWT)
    pipe_through (Auth.Controller.handleGetSecured)
    forwardf "/%s" Catalog.Controller.resource
    pipe_through (customResponseLogger)
}

The whole setup builds and runs without any errors or warnings. But there is one problem.
I "think" the function is eagerly evaluated. It always prints the status code as 200 regardless of the result.

Any guidance or sample code on how to achieve this will be hugely appreciated.