diff --git a/br-parser-tools-lib/br-parser-tools/private-lex/stx.rkt b/br-parser-tools-lib/br-parser-tools/private-lex/stx.rkt
index 07e80c3..6b5ab9a 100644
--- a/br-parser-tools-lib/br-parser-tools/private-lex/stx.rkt
+++ b/br-parser-tools-lib/br-parser-tools/private-lex/stx.rkt
@@ -159,27 +159,25 @@
 ;; and by "now", I mean it's been broken since before we 
 ;; moved to git. 
 (module+ test
-  (check-equal? (parse #'#\a null) #\a)
-  (check-equal? (parse #'"1" null) "1")
-  (check-equal? (parse #'(repetition 1 1 #\1) null)
+  (check-equal? (parse #'#\a) #\a)
+  (check-equal? (parse #'"1") "1")
+  (check-equal? (parse #'(repetition 1 1 #\1))
                 '(repetition 1 1 #\1))
-  (check-equal? (parse #'(repetition 0 +inf.0 #\1) null) '(repetition 0 +inf.0 #\1))
-  (check-equal? (parse #'(union #\1 (union "2") (union)) null)
+  (check-equal? (parse #'(repetition 0 +inf.0 #\1)) '(repetition 0 +inf.0 #\1))
+  (check-equal? (parse #'(union #\1 (union "2") (union)))
                 '(union #\1 (union "2") (union)))
-  (check-equal? (parse #'(intersection #\1 (intersection "2") (intersection))
-                       null)
+  (check-equal? (parse #'(intersection #\1 (intersection "2") (intersection)))
                 '(intersection #\1 (intersection "2") (intersection)))
-  (check-equal? (parse #'(complement (union #\1 #\2))
-                       null)
+  (check-equal? (parse #'(complement (union #\1 #\2)))
                 '(complement (union #\1 #\2)))
-  (check-equal? (parse #'(concatenation "1" "2" (concatenation)) null)
+  (check-equal? (parse #'(concatenation "1" "2" (concatenation)))
                 '(concatenation "1" "2" (concatenation)))
-  (check-equal? (parse #'(char-range "1" #\1) null) '(char-range #\1 #\1))
-  (check-equal? (parse #'(char-range #\1 "1") null) '(char-range #\1 #\1))
-  (check-equal? (parse #'(char-range "1" "3") null) '(char-range #\1 #\3))
-  (check-equal? (parse #'(char-complement (union "1" "2")) null)
+  (check-equal? (parse #'(char-range "1" #\1)) '(char-range #\1 #\1))
+  (check-equal? (parse #'(char-range #\1 "1")) '(char-range #\1 #\1))
+  (check-equal? (parse #'(char-range "1" "3")) '(char-range #\1 #\3))
+  (check-equal? (parse #'(char-complement (union "1" "2")))
                 '(char-complement (union "1" "2")))
-  (check-equal? (parse #'(char-complement (repetition 1 1 "1")) null)
+  (check-equal? (parse #'(char-complement (repetition 1 1 "1")))
                 '(char-complement (repetition 1 1 "1")))
   (check-exn #rx"not a character set"
-             (λ () (parse #'(char-complement (repetition 6 6 "1")) null))))
+             (λ () (parse #'(char-complement (repetition 6 6 "1"))))))