Comment #7 on issue 2353 by da...@teleport.com: #findString:startingAt:caseSensitive: broken for WideStrings http://code.google.com/p/pharo/issues/detail?id=2353 I hit this case in a Seaside/Pier image in the wild and the following expression will reproduce the problem taht I observed: | str | str := WideString new: 10 withAll: 45 asCharacter. str at: 5 put: (Character value: 8217). str findString: 'intro' startingAt: 1 caseSensitive: false. Yes ... the offending Character value was 8217. I don't know exactly how a character of that value got into the WideString, but it is there. The page where the character resides is: http://book.pharo-project.org/book/introduction/gettingstarted/ And the offending character is the $' in the phrase "if you haven’t done so already"... The Pier image is running with a WAComancheAdaptor that is doing utf-8 encoding ... The takeaway is that it is very possible to create an instance of WideString with Characters whose values are larger than 256 (the size of the matchTable)....