Index: test-fmt.scm
===================================================================
--- test-fmt.scm	(revision 23035)
+++ test-fmt.scm	(working copy)
@@ -342,6 +342,15 @@
 (test "foo   abc def ghi   \n      jkl mno       \n"
       (fmt #f (with-width 20 (columnar 6 (dsp "foo") (wrap-lines "abc def ghi jkl mno")))))
 
+(test          ;; test divide by zero error
+ "The  quick
+brown  fox
+jumped
+over   the
+lazy dog
+"
+ (fmt #f (with-width 10 (justify "The quick brown fox jumped over the lazy dog"))))
+
 (test "his message
 (http://lists.nongnu.org/archive/html/chicken-users/2010-10/msg00171.html)
 to the chicken-users
Index: fmt.setup
===================================================================
--- fmt.setup	(revision 23035)
+++ fmt.setup	(working copy)
@@ -1,4 +1,4 @@
-(define version "0.705")
+(define version "0.706")
 
 (compile -s -O2 -d0 -j fmt -o fmt.so fmt-chicken.scm)
 (compile -s -O2 -d0 fmt.import.scm)
Index: fmt-column.scm
===================================================================
--- fmt-column.scm	(revision 23035)
+++ fmt-column.scm	(working copy)
@@ -311,21 +311,29 @@
       (apply-cat ls))
      st)
     (wrap-fold (string-concatenate-reverse buffer)
-               st (fmt-width st) string-length print-line)))
+               st (fmt-width st)
+               (or (fmt-string-width st) string-length)
+               print-line)))
 
 (define (justify . ls)
   (lambda (st)
     (let ((width (fmt-width st))
+          (get-width (or (fmt-string-width st) string-length))
           (output (fmt-writer st))
           (buffer '()))
       (define (justify-line ls st)
         (if (null? ls)
             (nl st)
-            (let* ((sum (fold (lambda (s n) (+ n (string-length s))) 0 ls))
+            (let* ((sum (fold (lambda (s n) (+ n (get-width s))) 0 ls))
                    (len (length ls))
                    (diff (max 0 (- width sum)))
-                   (sep (make-string (quotient diff (- len 1)) #\space))
-                   (rem (remainder diff (- len 1))))
+                   (sep (make-string (if (= len 1)
+                                         0
+                                         (quotient diff (- len 1)))
+                                     #\space))
+                   (rem (if (= len 1)
+                            diff
+                            (remainder diff (- len 1)))))
               (output
                (call-with-output-string
                  (lambda (p)
@@ -347,7 +355,7 @@
         (apply-cat ls))
        st)
       (wrap-fold (string-concatenate-reverse buffer)
-                 st width string-length justify-line justify-last))))
+                 st width get-width justify-line justify-last))))
 
 (define (fmt-file path)
   (lambda (st)