runtime: TripleDES is not allowing 16 byte keys

This works on full framework, but not core. This is a simple alteration of the dotnet new to isolate the problem (only other change is to add net452 to project.json).

using System;
using System.Security.Cryptography;
using System.Text;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var d = TripleDES.Create();
            d.Key = ASCIIEncoding.ASCII.GetBytes("1234567890123456");
            Console.WriteLine("Hello World!");
        }
    }
}

Running the above under net452 works fine, but under netcoreapp10 results in:

Unhandled Exception: System.Security.Cryptography.CryptographicException: Specified key is not a valid size for this alg
orithm.
   at System.Security.Cryptography.SymmetricAlgorithm.set_Key(Byte[] value)
   at System.Security.Cryptography.TripleDES.set_Key(Byte[] value)
   at ConsoleApplication.Program.Main(String[] args)