diff --git a/module/mes/scm.mes b/module/mes/scm.mes
index 6172a4ba..6cb6ed59 100644
--- a/module/mes/scm.mes
+++ b/module/mes/scm.mes
@@ -213,20 +213,25 @@
    (>= (string-length string) (string-length prefix))
    (equal? (substring string 0 (string-length prefix)) prefix)))
 
-(define (string->number s . radix)
-  (if (and (pair? radix) (not (= (car radix) 10))) '*STRING->NUMBER:RADIX-NOT-SUPPORTED
-      (let* ((lst (string->list s))
-             (sign (if (char=? (car lst) #\-) -1 1))
-             (lst (if (= sign -1) (cdr lst) lst)))
-        (let loop ((lst lst) (n 0))
-          (if (null? lst) (* sign n)
-              (loop (cdr lst) (+ (* n 10) (- (char->integer (car lst)) (char->integer #\0)))))))))
+(define (string->number s . rest)
+  (let* ((radix (if (null? rest) 10 (car rest)))
+         (lst (string->list s))
+         (sign (if (char=? (car lst) #\-) -1 1))
+         (lst (if (= sign -1) (cdr lst) lst)))
+    (let loop ((lst lst) (n 0))
+      (if (null? lst) (* sign n)
+          (let ((i (char->integer (car lst))))
+            (loop (cdr lst) (+ (* n radix) (- i (if (<= i (char->integer #\9)) (char->integer #\0)
+                                                    (- (char->integer #\a) 10))))))))))
 
-(define (number->string n)
-  (let ((sign (if (< n 0) '(#\-) '())))
+(define (number->string n . rest)
+  (let* ((radix (if (null? rest) 10 (car rest)))
+         (sign (if (< n 0) '(#\-) '())))
     (let loop ((n (abs n)) (lst '()))
-      (let* ((lst (cons (integer->char (+ (remainder n 10) (char->integer #\0))) lst))
-             (n (quotient n 10)))
+      (let* ((i (remainder n radix))
+             (lst (cons (integer->char (+ i (if (<= i 10) (char->integer #\0)
+                                                (- (char->integer #\a) 10)))) lst))
+             (n (quotient n radix)))
         (if (= 0 n) (list->string (append sign lst))
             (loop n lst))))))