Deserialisation error of Serialised enum with struct

Here deserialisation is returning Syntax("invalid value: integer `10`, expected field index 0 <= i < 1"):

```
#[derive(Serialize, Deserialize, Debug)]
enum Test
{
Inner {val: i32}
}

fn main()
{
let ser = rmp_serde::to_vec_named(&Test::Inner {val: 10}).unwrap();
println!("{:?}", ser);
let de: Test = rmp_serde::from_slice(&ser).unwrap();
println!("{:?}", de);
}
```

Serialised form is [146, 0, 129, 10] and it looks invalid.