pusher-http-dotnet: Error with dotnet client

Using PusherClient 0.5.1 with WebSocket4Net 0.15.2.

After a pile of NuGet updates, my existing code now breaks when I try to Connect(). As below:

        var pusher = new Pusher("redacted");
        pusher.Connect();

Error is:

System.MissingMethodException HResult=0x80131513 Message=Method not found: ‘Void WebSocket4Net.WebSocket…ctor(System.String, System.String, System.Collections.Generic.List1<System.Collections.Generic.KeyValuePair2<System.String,System.String>>, System.Collections.Generic.List1<System.Collections.Generic.KeyValuePair2<System.String,System.String>>, System.String, System.String, WebSocket4Net.WebSocketVersion, System.Net.EndPoint)’. Source=PusherClient StackTrace: at PusherClient.Connection.Connect() at PusherClient.Pusher.Connect()