How to modify `request.params.id` type with declaration merging in Typescript/Express?

Question

I've successfully added currentUser to Express' Request interface:

declare global {
  namespace Express {
    export interface Request {
      currentUser?: User;
    }
  }
}

However, I also want to specify that the Request's path param req.params.id (where req is of type Express.Request) is a Number and not a String (which is the default type of params from the Request interface). But I'm not sure how to do this as it is nested inside of the ParamsDictionary interface. Here's a snippet of what I tried unsuccessfully:

declare global {
  namespace Express {
    export interface ParamsDictionary extends Request {
      id: number;
    }
  }
}

For reference, Request is defined like this in the default Express/Typescript config file:

interface Request<
        P = core.ParamsDictionary,
        ResBody = any,
        ReqBody = any,
        ReqQuery = core.Query,
        Locals extends Record<string, any> = Record<string, any>
    > extends core.Request<P, ResBody, ReqBody, ReqQuery, Locals> {}

This is why I've been trying to modify the ParamsDictionary, which I assume contains the path params that can be found in req.params of a middleware or route function. I still get errors such as this one, which proves that Typescript still assumes that the id is a string (which I confirm it isn't. it is passed as number):