Issue #2043 has been updated by Vit Ondruch. In following example, just characters from US-ASCII are used and in this case the addition works well. s = 'abc' a = s.encode 'cp1250' b = s.encode 'utf-8' c = a + b ---------------------------------------- http://redmine.ruby-lang.org/issues/show/2043 ---------------------------------------- http://redmine.ruby-lang.org