Hi, I propose a new test case, which unfortunately fails right now... (deftest values.previous (equal (iter (repeat 3) (for (values a b) = (floor 5 2)) (for p-a previous a) (for p-b previous b) (collect (list a b p-a p-b))) '((2 1 nil nil) (2 1 2 1) (2 1 2 1))) T) Just wanted to let you know that I was stumbling over this as a user - I probably could not fix it myself.... Cheers, Kilian