I guess you are modifying the value of *var*, which is not allowed if it is a quoted list. That's why you need e.g. (list .. ..) or (copy-tree '(.. ..)) instead of '(.. ..).

http://stackoverflow.com/questions/10365470/modifying-a-list-passed-as-a-parameter-gives-different-results-in-sbcl-and-clisp

- Willem