TO_TSVECTOR acts differently with national charcters

Query:

SELECT strip(to_tsvector('simple','toop/6 foo bar')),strip(to_tsvector('simple','tüüp/6 foo bar'));

PosgreSQL 9.3.5, Collation - Estonian

Results are:
'bar' 'foo' 'toop/6'
'/6' 'bar' 'foo' 'tüüp'

The string is converted to vector differently, when the string contains national charcters "äöüõžš".

Mart Palmas