diff --git a/contrib/05.r7rs/scheme/case-lambda.scm b/contrib/05.r7rs/scheme/case-lambda.scm
index fff2b26c..6a6ca432 100644
--- a/contrib/05.r7rs/scheme/case-lambda.scm
+++ b/contrib/05.r7rs/scheme/case-lambda.scm
@@ -1,28 +1,25 @@
 (define-library (scheme case-lambda)
   (import (scheme base))
 
+  (define (length+ list)
+    (if (pair? list)
+        (+ 1 (length+ (cdr list)))
+        0))
+
   (define-syntax case-lambda
     (syntax-rules ()
       ((case-lambda (params body0 ...) ...)
        (lambda args
          (let ((len (length args)))
            (letrec-syntax
-               ((cl (syntax-rules ::: ()
+               ((cl (syntax-rules ()
                       ((cl)
                        (error "no matching clause"))
-                      ((cl ((p :::) . body) . rest)
-                       (if (= len (length '(p :::)))
-                           (apply (lambda (p :::)
-                                    . body)
-                                  args)
-                           (cl . rest)))
-                      ((cl ((p ::: . tail) . body)
-                           . rest)
-                       (if (>= len (length '(p :::)))
-                           (apply
-                            (lambda (p ::: . tail)
-                              . body)
-                            args)
+                      ((cl (formal . body) . rest)
+                       (if (if (list? 'formal)
+                               (= len (length 'formal))
+                               (>= len (length+ 'formal)))
+                           (apply (lambda formal . body) args)
                            (cl . rest))))))
              (cl (params body0 ...) ...)))))))