Pippi Longstocking tag problem

Posted under Tags

Whenever I try to edit the tags and add a character tag for Pippi Longstocking to a picture, the first result in the dropdown menu is 'pippi_långstrump' but when I hit submit, I get an error message that says

Couldn't add tag: 'pippi_långstrump' must consist of only ASCII characters.

If this is true, then how are there already 15 pictures here with that tag? Should the 'pippi_långstrump' tag be deleted and replaced with something more ASCII friendly (whatever that means)?