Killing an AsyncHttpServer

[def_pri_pub]

So I've got some code like this:
    
    
    import asyncDispatch
    import asynchttpserver
    
    # Create the server object and state data
    var
      server = newAsyncHttpServer()
    let port = 8000
    
    # ...
    
    proc handleRequest(req: Request) {.async.}=
      ## Handle an incomming connection
      var killServer = false
      
      # ...
      
      if killServer:
        server.close()
      
      # Write a response
      var headers = newHttpHeaders()
      headers.add("Content-Type", "text/html")
      await req.respond(Http200, mkPage(pageViews, killServer), headers)
    
    
    # Handle requests
    echo("Listening for connections on http://localhost:"; & $port & "/")
    waitFor server.serve(Port(port), handleRequest)
    

If I try to call server.close() I keep on getting this error: 
    
    
    Server.nim(74, 15) Error: type mismatch: got (AsyncHttpServer, Port, proc 
(req: Request): Future[system.void]{.locks: <unknown>.})
    but expected one of:
    proc serve(server: AsyncHttpServer; port: Port;
              callback: proc (request: Request): Future[void]; address = ""): 
Future[void]
    

I've tried creating a wrapper async function around the close call, that didn't 
work. I tried using an event callback, that didn't work either. Both other 
produced the same compilation errors. What's going on here?