In SELECT SNIPPET, how to pass string option with spaces?

With SELECT SNIPPET, I want to set option chunk_separator to value ' ~ ' (without quotes), but I can’t figure out how to do that. In following example the spaces around ~ are ignored:

SELECT id, SNIPPET(MyGetContent(id), :Query,
             'query_mode=1', 'chunk_separator= ~ '
           ) as snippet
FROM SongSearch ...

I’ve used CALL SNIPPETS earlier and there this is trivial:

CALL SNIPPETS(:Content, 'SongSearch', :Query, 1 AS query_mode,
  ' ~ ' AS chunk_separator

Spaces around the values in SNIPPET() are just ignored now (although a space AFTER ~ should work)