;; we're supposed to soldier on bravely, and so we have to deal with
;; the unsupplied-MINCOL-and-COLINC case without blowing up.
(when (and mincol colinc)
- (do ((chars (+ (length string) minpad) (+ chars colinc)))
+ (do ((chars (+ (length string) (max minpad 0)) (+ chars colinc)))
((>= chars mincol))
(dotimes (i colinc)
(write-char padchar stream))))