Flowtype error on node http Server listen method

server.js

const createServer = require('http').createServer
const app = require('./http/app') // Express app

const server = createServer(app)

server.listen(port)
/**
 * ^ This is where I'm getting the Flow error:
 * 
 * call of method `listen`: /Users/shane/projects/blockpop/server/src/server.js:22
 * Function cannot be called on any member of intersection type
 * intersection: /Users/shane/projects/blockpop/server/src/server.js:22
 * Member 1:
 * function type: /private/tmp/flow/flowlib_3f09764c/node.js:696
 * Error:
 * boolean: /Users/shane/projects/blockpop/server/src/server.js:22
 * This type is incompatible with
 * number: /private/tmp/flow/flowlib_3f09764c/node.js:696
 * Member 2:
 * function type: /private/tmp/flow/flowlib_3f09764c/node.js:697
 * Error:
 * boolean: /Users/shane/projects/blockpop/server/src/server.js:22
 * This type is incompatible with
 * string: /private/tmp/flow/flowlib_3f09764c/node.js:697
 * Member 3:
 * function type: /private/tmp/flow/flowlib_3f09764c/node.js:698
 * Error:
 * boolean: /Users/shane/projects/blockpop/server/src/server.js:22
 * This type is incompatible with
 * object type: /private/tmp/flow/flowlib_3f09764c/node.js:698
 */
 
 // Here's the http declaration Flow is using, which is referenced in the Flow error above:
 declare module "http" {
  declare class Server extends net$Server {
    listen(port: number, hostname?: string, backlog?: number, callback?: Function): Server; // line 696
    listen(path: string, callback?: Function): Server; // line 697
    listen(handle: Object, callback?: Function): Server; // line 698
    close(callback?: Function): Server;
    maxHeadersCount: number;
    setTimeout(msecs: number, callback: Function): Server;
    timeout: number;
  }

  declare class ClientRequest extends http$ClientRequest {}
  declare class IncomingMessage extends http$IncomingMessage {}

  declare function createServer(listener?: Function): Server;
  declare function request(
    options: Object | string,
    callback?: (response: IncomingMessage) => void
  ): ClientRequest;
  declare function get(
    options: Object | string,
    callback?: (response: IncomingMessage) => void
  ): ClientRequest;
}

Flow is inferring the type of port to be boolean. The error shows that there are 3 possible ways to call listen, one that takes a number, one a string, and one an Object—and boolean is incompatible with all of those.