Segfault (SIGSEGV) in queries with non-ascii characters

[janaleible]

I have an index that is built on Wikipedia articles. Whenever a query contains a non-ascii character, something (I can't exactly locate the error, but it's definitely below Index.query()) throws a segmentation fault. This happens for '–' and 'ō', but not 'é' (presumably because the latter is part of ascii-256?).