MailChimp API .NET SSL TLS Error

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;

namespace SSLTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var task = Tester();
            Task.WaitAll(task);
            Console.WriteLine("press any key to quit");
            Console.ReadLine();          
        }

        public static async Task Tester()
        {
            try
            {
                // Watch this var to see it's set to Tls | Ssl3
                var temp = ServicePointManager.SecurityProtocol;

                // Uncomment this line to correct error
                // ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

                HttpClient client = new HttpClient();
                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", "[API KEY GOES HERE]");
                var response = await client.GetAsync("https://us9.api.mailchimp.com/3.0/");
                var result = await response.Content.ReadAsStringAsync();
                Console.WriteLine(result);
            }
            catch(Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }
 
    }
}