Since it has been declared that frozen_string_literal will print warnings in Ruby 3.4. and will be mandatory in the future I must warn, that ruby still doesn't have built in method for sorting by UTF-8 characters. Most of string methods work OK with UTF-8 strings, but not sort. I've been using sort_alphabetical gem [ https://github.com/grosser/sort_alphabetical ] for a long time and it works good for me. Problem is that it depends on unicode_utils gem [ https://github.com/lang/unicode_utils ] which looks like a dead repository, since repository owner has not been active for a decade. And unicode_utils use a lot of code which is not complied with frozen_string_literal. I am proposing to include UTF-8 sort (ex. sort_by_utf) method into next ruby version or at least include (and correct) those two gems in a future Ruby distribution. Thanks by TheR