System.Int64 is not a supported primitive type

I'm trying to use the HTTP Webservice Activity, but it fails on parsing JSON containing long INTs (Int64):

System.ArgumentException: 'System.Int64' is not a supported primitive type.
Parameter name: value at Microsoft.Activities.Dynamic.DynamicPrimitive..ctor(Object value)
at Microsoft.Activities.Dynamic.JsonHelper.AsDynamicItem(JsonValue obj)
at Microsoft.Activities.Dynamic.JsonHelper.TryCreateDynamicObject(JsonValue obj, DynamicItem& dynamicObject)
at Microsoft.Activities.Dynamic.JsonHelper.JsonToDynamic(JsonValue obj)
at Microsoft.Activities.Dynamic.DynamicJsonArray..ctor(JsonArray jsonArray)
at Microsoft.Activities.Dynamic.JsonHelper.AsDynamicItem(JsonValue obj)
at Microsoft.Activities.DynamicValue.ParseJson(String json)
at Microsoft.Activities.Messaging.HttpActivityHelpers.TryDeserializeResponseContent(Uri uri, Byte[] bytes, HttpStatusCode statusCode, String mediaType, Type typeToDeserialize, String accept, Object& result, Exception& exception)

Is there any chance of circumventing this? Twitter Tweet IDs are unfortunately Int64, hence I will need to be able to use Int64 if I want to parse twitter feeds: https://dev.twitter.com/docs/api/1/get/statuses/user_timeline