json function question

Hi !

I'm running "PostgreSQL 9.5.1 on i686-pc-linux-gnu, compiled by
gcc-4.4.real (Debian 4.4.5-8) 4.4.5, 32-bit"

I'm trying out json functions and stumbled on a problem with
json_populate_record.
To try out the function I decided to take records from table test convert
them to json and immediately repopulate them back into records of type
test, but it fails with this message:

ERROR: malformed array literal: "["abc","def","fgh"]"
DETAIL: "[" must introduce explicitly-specified array dimensions.
********** Error **********

ERROR: malformed array literal: "["abc","def","fgh"]"
SQL state: 22P02
Detail: "[" must introduce explicitly-specified array dimensions.

Is it a bug or how am I supposed to use the populate function ?
If I try an equivalent example with hstore it works well.

I have this table, data and query:

create table test
(
id int,
txt text,
txt_arr text[],
f float
);

insert into test
values
(1,'jkl','{abc,def,fgh}',3.14159),(2,'hij','{abc,def,fgh}',3.14159),(2,null,null,null),(3,'def',null,0);

select j, json_populate_record(null::test, j)
from
(
select to_json(t) as j from test t
) r

Best Regards
Dan S