Error ora-00932 when selecting from table defined as type with nested type

Ora-00932 is raised when selecting from a table defined as type which has nested type using a where clause.
For example - objects created a follows:

Table Definition

table T (t a_type);

Type definition

Type a_type
    a char,
    b b_type,
    c varchar2(10),
    d varchar2(20);

Type b_type
    a varchar2(10),
    b number,
    c char(1);

select * from t; work fine. However select * from t where t = 'ABC' fails with ora-00932 inconsistent data type.

Is there any way around this?