TS2339: Property files does not exist on type

[rzinnatullin]

TypeScript project.
Installed npm i @types/express-busboy --save-dev.

My router method:

router.post("uploads", async (req, res) => {
    console.log(req.files);
}

Got compilation error on the console.log line:

error TS2339: Property 'files' does not exist on type 'Request<{ runId: string; } & { requestId: string; }, any, any, ParsedQs, Record<string, any>>'.

I understand that bb.extend(app... does nothing with the type info, thus we get the compilation error.
But since there's d.ts support for this package, how developers supposed to be accessing req.files w/o falling back to pure JavaScript way of thinking?

If it matters, I have "noImplicitAny": true compiler option set in tsconfig.json, so it's restricted to cast req to any.