(flex:with-input-from-sequence (s (babel:string-to-octets "<![IGNORE[ ]]><!-- -->" :encoding :utf-8)) (cxml:parse-dtd-stream s)) errors with Document not well-formed: Unexpected character #\!. Context: Line 1, column 17 in NIL [Condition of type CXML:WELL-FORMEDNESS-VIOLATION] but parses OK with whitespace between ]]> and <!-- (for a real example, see line 396 in http://docbook.org/xml/4.3/dbpoolx.mod) it looks like P/IGNORE-SECT in cxml/xml/xml-parse.lisp should unread 1 rune after matching ]]> (or exit the loop sooner so it doesn't read an extra).