Query buffer allocate error in copy_statement_with_parameters

I'm getting the error message "Query buffer allocate error in
copy_statement_with_parameters" when calling a function with a
parameter.

The very simple function was created like this:

CREATE OR REPLACE FUNCTION pvsystem.spclearloginfails
(_seconds integer)
RETURNS void AS $$
BEGIN
DELETE FROM LoginFails WHERE extract(epoch FROM NOW()) -
extract(epoch FROM LastFail) > _seconds;
END;
$$
LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT
SECURITY DEFINER COST 100;

Calling SQLPrepare() works fine. Calling SQLDescribeParam() works fine.
Calling SQLBindParameter() works fine.
SQLExecute returns the above error.

The data buffer for the parameter is 10 bytes long. The contents are
"300" followed by nulls. length_or_ind is 3.

Doesn't seem like there's very much that can go wrong here.

The server is version 9.2.7 and the ODBC driver is version 08.03.0200.
Running on OpenSUSE 13.1.

Thanks!
John