diff --git a/piclib/built-in.scm b/piclib/built-in.scm
index 2dcaade4..680b0e16 100644
--- a/piclib/built-in.scm
+++ b/piclib/built-in.scm
@@ -280,14 +280,19 @@
      (lambda (form r compare)
        (let ((bindings (cadr form))
              (body (cddr form)))
-         (let ((vars (map car bindings)))
+         (let ((vars (map car bindings))
+               (gensym (lambda (var)
+                         (string->symbol
+                          (string-append
+                           "parameterize-"
+                           (symbol->string var))))))
            `(,(r 'let) (,@(map (lambda (var)
-                                 `(,(r var) (,var)))
+                                 `(,(r (gensym var)) (,var)))
                             vars))
               ,@bindings
               (,(r 'let) ((,(r 'result) (begin ,@body)))
                 ,@(map (lambda (var)
-                         `(,(r 'parameter-set!) ,var ,(r var)))
+                         `(,(r 'parameter-set!) ,var ,(r (gensym var))))
                        vars)
                 ,(r 'result))))))))
 
@@ -680,14 +685,14 @@
 (define-library (scheme cxr)
   (import (scheme base))
 
-  (define (caaar  p) (car  (caar p)))
-  (define (caadr  p) (car  (cadr p)))
-  (define (cadar  p) (car  (cdar p)))
-  (define (caddr  p) (car  (cddr p)))
-  (define (cdaar  p) (cdr  (caar p)))
-  (define (cdadr  p) (cdr  (cadr p)))
-  (define (cddar  p) (cdr  (cdar p)))
-  (define (cdddr  p) (cdr  (cddr p)))
+  (define (caaar p) (car (caar p)))
+  (define (caadr p) (car (cadr p)))
+  (define (cadar p) (car (cdar p)))
+  (define (caddr p) (car (cddr p)))
+  (define (cdaar p) (cdr (caar p)))
+  (define (cdadr p) (cdr (cadr p)))
+  (define (cddar p) (cdr (cdar p)))
+  (define (cdddr p) (cdr (cddr p)))
   (define (caaaar p) (caar (caar p)))
   (define (caaadr p) (caar (cadr p)))
   (define (caadar p) (caar (cdar p)))