invalid byte sequence for encoding "UTF8"

I am running into a difference in behavior that I think is related to the psqlODBC driver between Windows and Linux. On Windows x86 using the Windows ODBC manager and psqlODBC 8.4.2 ANSI driver I have some C++ code that executes the following SQL statements and inserts into a Windows x86 PostgreSQL 8.4.2 database.

CREATE TABLE luke_test(a TEXT);
INSERT INTO luke_test (a) VALUES('ý');
INSERT INTO luke_test (a) VALUES('þ');
INSERT INTO luke_test (a) VALUES('ÿ');
SELECT * FROM luke_test;
--ý
--þ
--ÿ
DROP TABLE luke_test;

Where the value being insered is a single character byte. This seems to work fine in Windows. I am not wanting to treat the bytes with there 8th bit set as multi-byte characters.

However, if I compile and run the same C++ code on Linux x64 using unixODBC 2.2.15pre ODBC manager and psqlODBC 8.4.2 ANSI driver inserting into the before mentioned Windows x86 PostreSQL 8.4.2 database I get different behavior.

CREATE TABLE luke_test(a TEXT);
INSERT INTO luke_test (a) VALUES('ý');
Error executing "INSERT INTO luke_test (a) VALUES('ý');": ERROR:
invalid byte sequence for encoding "UTF8": 0xfd;
Error while executing the query
INSERT INTO luke_test (a) VALUES('þ');
Error executing "INSERT INTO luke_test (a) VALUES('þ');": ERROR:
invalid byte sequence for encoding "UTF8": 0xfe;
Error while executing the query
INSERT INTO luke_test (a) VALUES('ÿ');
Error executing "INSERT INTO luke_test (a) VALUES('ÿ');": ERROR:
invalid byte sequence for encoding "UTF8": 0xff;
Error while executing the query
SELECT * FROM luke_test;
DROP TABLE luke_test;

Which leads me to believe that my environment on Linux is trying to treat the character bytes as multi-byte characters. I have tried SET client_encoding='ANSI_SQL' before I execute the inserts and that does not seem to help the situation. Can anyone help explain the difference in behavior that I am seeing and suggest a workaround that does not involve encoding the character bytes as UTF8.

Luke