Swift 3.0: Data to Json [String: Any]

Evening, I'm trying to creating an APIClient, but I'm having a problem with a warning: APIClient.swift:53:81: Cast from 'Data' to unrelated type '[String : Any]' always fails

In this code I'm trying to convert Data into JSON as a dictionary [String : Any].

I guess the compiler can't know if this cast could or could not be possible so it throws the error, but I'm pretty sure it will work. So how can I avoid this warning or how can I write safer code?

case 200:
         do {
            let json = try JSONSerialization.data(withJSONObject: data!, options: []) as? [String : Any]
            completion(json, HTTPResponse, nil)
         } catch let error {
             completion(nil, HTTPResponse, error)
         }