I've been working off of CVS head and had a problem with serializing nicely formatted indented xml. I am using sbcl 0.9.7 that has Unicode support rune-is-character is in the *features*. I was running into an error along the lines of "The value 10 is not of type CHARACTER." and "The value 32 is not of type CHARACTER.". I tracked it down a bit and found in unparse.lisp a couple of lines (%write-rune 10 sink) whereas most of the occurrences in the file were more like (%write-rune #/U+000A sink) Changing these seems to fix it. I take it you've changed the interface to this function at some point and just didn't get all the references? Patch attached. Nathan