Cannot create a type in pg_catalog

Should this work, or at least give a more appropriate error message?

demo=# SELECT version();
version

------------------------------------------------------------------------------------------
PostgreSQL 8.2.4 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC)
3.4.2 (mingw-special)
(1 row)

demo=# SELECT rolname, rolsuper, rolcatupdate FROM pg_authid;
rolname | rolsuper | rolcatupdate
----------+----------+--------------
postgres | t | t
(1 row)

demo=# CREATE TYPE pg_catalog.mytype AS (data text);
ERROR: permission denied to create "pg_catalog.mytype"
DETAIL: System catalog modifications are currently disallowed.

I can successfully create functions in pg_catalog, just not types or
relations.

Regards, Dave.