diff --git a/collects/tests/mzscheme/pconvert.ss b/collects/tests/mzscheme/pconvert.ss
index effee2d..1c71961 100644
--- a/collects/tests/mzscheme/pconvert.ss
+++ b/collects/tests/mzscheme/pconvert.ss
@@ -119,13 +119,13 @@
 
      (make-test 3/2 3/2 '(+ 1 1/2) 3/2 3/2 '(+ 1 1/2) 3/2 3/2)
 
-     (make-test (list 1) '(list 1) '(list 1) '(list 1) '`(1) '`(1) '`(1) '(cons 1 null))
+     (make-test (list 1) '(list 1) '(list 1) '(list 1) '`(1) '`(1) '`(1) '(cons 1 empty))
      (make-test (list 1/2) '(list 1/2) '(list 1/2) '(list 1/2)
 		'`(1/2) '`(1/2)  '`(1/2)
-		'(cons 1/2 null))
+		'(cons 1/2 empty))
      (make-test (list 3/2) '(list 3/2) '(list (+ 1 1/2)) '(list 3/2)
 		'`(3/2) '`(,(+ 1 1/2)) '`(3/2)
-		'(cons 3/2 null))
+		'(cons 3/2 empty))
      (make-test (list 1/2+1/2i) 
 		'(list 1/2+1/2i) 
 		'(list (+ 1/2 (* 0+1i 1/2))) 
@@ -133,7 +133,7 @@
 		'`(1/2+1/2i) 
 		'`(,(+ 1/2 (* 0+1i 1/2)))  
 		'`(1/2+1/2i)
-		'(cons 1/2+1/2i null))
+		'(cons 1/2+1/2i empty))
      (make-test (list 3/2+1/2i) 
 		'(list 3/2+1/2i) 
 		'(list (+ (+ 1 1/2) (* 0+1i 1/2))) 
@@ -141,7 +141,7 @@
 		'`(3/2+1/2i) 
 		'`(,(+ (+ 1 1/2) (* 0+1i 1/2)))  
 		'`(3/2+1/2i)
-		'(cons 3/2+1/2i null))
+		'(cons 3/2+1/2i empty))
      (make-test (list 1/2+3/2i) 
 		'(list 1/2+3/2i) 
 		'(list (+ 1/2 (* 0+1i (+ 1 1/2)))) 
@@ -149,7 +149,7 @@
 		'`(1/2+3/2i) 
 		'`(,(+ 1/2 (* 0+1i (+ 1 1/2))))  
 		'`(1/2+3/2i)
-		'(cons 1/2+3/2i null))
+		'(cons 1/2+3/2i empty))
      (make-test (list 3/2+3/2i) 
 		'(list 3/2+3/2i) 
 		'(list (+ (+ 1 1/2) (* 0+1i (+ 1 1/2)))) 
@@ -157,7 +157,7 @@
 		'`(3/2+3/2i) 
 		'`(,(+ (+ 1 1/2) (* 0+1i (+ 1 1/2))))  
 		'`(3/2+3/2i)
-		'(cons 3/2+3/2i null))
+		'(cons 3/2+3/2i empty))
 
      (make-same-test (vector 0 0 0 0 0 0 0 0 0 0) '(vector 0 0 0 0 0 0 0 0 0 0))
      (make-same-test #t 'true)
@@ -168,7 +168,7 @@
      (make-same-test (delay 1) '(delay ...))
      (make-same-test (let-struct a (a) (make-a 3)) '(make-a 3))
      (make-same-test (box 3) '(box 3))
-     (make-test null 'null 'null 'null '`() '`() '`() 'null)
+     (make-test null 'empty 'empty 'empty '`() '`() '`() 'empty)
      (make-same-test add1 'add1)
      (make-same-test (void) '(void))
      (make-same-test (unit (import) (export)) '(unit ...))
@@ -209,16 +209,16 @@
 		       ht)
 		     '(make-hash-table))
      (make-test (list 'a (box (list ())) (cons 1 '()))
-		'(list (quote a) (box (list null)) (list 1))
-		'(list (quote a) (box (list null)) (list 1))
-		'(list (quote a) (box (list null)) (list 1))
+		'(list (quote a) (box (list empty)) (list 1))
+		'(list (quote a) (box (list empty)) (list 1))
+		'(list (quote a) (box (list empty)) (list 1))
 		'`(a ,(box `(())) (1))
 		'`(a ,(box `(())) (1))
 		'`(a ,(box `(())) (1))
 		'(cons 'a 
-		       (cons (box (cons null null))
-			     (cons (cons 1 null)
-				   null))))
+		       (cons (box (cons empty empty))
+			     (cons (cons 1 empty)
+				   empty))))
      (make-test (let ([x (list 1)]) (set-car! x x) x)
 		'(shared ([-0- (list -0-)]) -0-)
 		'(shared ([-0- (list -0-)]) -0-)
@@ -226,7 +226,7 @@
 		'(shared ([-0- `(,-0-)]) -0-)
 		'(shared ([-0- `(,-0-)]) -0-)
 		'(shared ([-0- `(,-0-)]) -0-)
-		'(shared ([-0- (cons -0- null)]) -0-))
+		'(shared ([-0- (cons -0- empty)]) -0-))
      (make-test (let ([x (list 1)]) (set-cdr! x x) x)
 		'(shared ([-0- (cons 1 -0-)]) -0-)
 		'(shared ([-0- (cons 1 -0-)]) -0-)
@@ -256,14 +256,14 @@
 			  [-4- `(2 3)])
 		   `(,-1- ,-3- ,-4- (2 3)))
 		'(shared ([-1- (cons -1- 
-				     (cons (cons 1 (cons 2 (cons 3 null)))
-					   (cons (cons 2 (cons 3 null))
-						 null)))])
+				     (cons (cons 1 (cons 2 (cons 3 empty)))
+					   (cons (cons 2 (cons 3 empty))
+						 empty)))])
 		   (cons -1- 
-			 (cons (cons 1 (cons 2 (cons 3 null)))
-			       (cons (cons 2 (cons 3 null)) 
-				     (cons (cons 2 (cons 3 null))
-					   null))))))
+			 (cons (cons 1 (cons 2 (cons 3 empty)))
+			       (cons (cons 2 (cons 3 empty)) 
+				     (cons (cons 2 (cons 3 empty))
+					   empty))))))
      (make-no-cons-test (let* ([a (list 1 2 3)]
 			       [b (list 1 a (cdr a))])
 			  (set-car! b b)
@@ -326,8 +326,8 @@
   (define test-shared (make-test-shared #t))
   (define test-not-shared (make-test-shared #f))
 
-  (test-not-shared #t true)
-  (test-not-shared #f false)
+  (test-not-shared #t 'true)
+  (test-not-shared #f 'false)
   (test-not-shared 1 1)
   (test-not-shared 3276832768327683276832768327683276832768
 		   3276832768327683276832768327683276832768)
@@ -353,7 +353,8 @@
 (arity-test build-share 1 1)
 (arity-test get-shared 1 2)
 (arity-test print-convert-expr 3 3)
-(test 'null print-convert '())
+
+(test 'empty print-convert '())
 
 (let ([pc
        (lambda (pv)