diff --git a/period.scm b/period.scm
index 93c2b22..739ee9a 100644
--- a/period.scm
+++ b/period.scm
@@ -61,18 +61,15 @@
  ;; Converts list of start/stop markers to list of pairs of months -
  ;; periods.
  (define (period-markers->periods l)
-   (print "===")
    (let loop ((l l)
 	      (ps '())
 	      (cb #f))
-     (print l)
      (if (null? l)
 	 (if cb
 	     (reverse (cons (cons cb #f) ps))
 	     (reverse ps))
 	 (let ((m (car l))
 	       (rmt (if cb 'stop 'start)))
-	   (print "  m: " m)
 	   (if (eq? (car m) rmt)
 	       (if cb
 		   (loop (cdr l)
@@ -151,16 +148,16 @@
    (run-tests
     period
     (test-equal? sort-period-markers
-		 (sort-period-markers '((start 2023 1) (stop 2022 10) (start 2022 3)))
-		 '((start 2022 3) (stop 2022 10) (start 2023 1)))
+		 (sort-period-markers '((start (2023 1)) (stop (2022 10)) (start (2022 3))))
+		 '((start (2022 3)) (stop (2022 10)) (start (2023 1))))
     (test-equal? period-markers->periods
 	         (period-markers->periods
-		  '((start 2022 3) (stop 2022 10) (start 2023 1) (stop 2023 4)))
+		  '((start (2022 3)) (stop (2022 10)) (start (2023 1)) (stop (2023 4))))
 		 '(((2022 3) . (2022 10))
 		   ((2023 1) . (2023 4))))
     (test-equal? period-markers->periods-open
 	         (period-markers->periods
-		  '((start 2022 3) (stop 2022 10) (start 2023 1) (stop 2023 4) (start 2023 5)))
+		  '((start (2022 3)) (stop (2022 10)) (start (2023 1)) (stop (2023 4)) (start (2023 5))))
 		 '(((2022 3) . (2022 10))
 		   ((2023 1) . (2023 4))
 		   ((2023 5) . #f)))