--- /home/arthur/tmp/srfi-48.scm.~1~	2017-10-11 13:51:18.285549747 -0700
+++ /home/arthur/tmp/srfi-48.scm	2017-10-11 14:24:44.503147871 -0700
@@ -80,11 +80,13 @@
                        (new-frac
                         (substring temp-str 0 digits))
                      )
-                 (string-append
-                  (if carry? (number->string (+ 1 (string->number pre-str))) pre-str)
-                  "."
-                  new-frac
-                  exp-str)))
+		 (let ( (pre-str* (if (string=? pre-str "") "0" pre-str))
+		      )
+		   (string-append
+		    (if carry? (number->string (+ 1 (string->number pre-str*))) pre-str)
+		    "."
+		    new-frac
+		    exp-str))))
          ) ) )
  
          (define (format-fixed number-or-string width digits) ; returns a string