diff --git a/src/cal-day.scm b/src/cal-day.scm
index c796114..120df80 100644
--- a/src/cal-day.scm
+++ b/src/cal-day.scm
@@ -118,6 +118,32 @@
  (define (cal-day-tests!)
    (run-tests
     cal-day
+    (test-equal? make-cal-day
+		 (make-cal-day 2023 5 10)
+		 `(,TAG-CAL-DAY 2023 5 10))
+    (test-true cal-year-leap?
+	       (cal-year-leap? 2000))
+    (test-true cal-year-leap?
+	       (cal-year-leap? 2024))
+    (test-false cal-year-leap?
+		(cal-year-leap? 2023))
+    (test-false cal-year-leap?
+		(cal-year-leap? 1900))
+    (test-eq? cal-month-days
+	      (cal-month-days 2023 5)
+	      31)
+    (test-eq? cal-month-days
+	      (cal-month-days 2023 2)
+	      28)
+    (test-eq? cal-month-days
+	      (cal-month-days 2024 2)
+	      29)
+    (test-true cal-day?
+	       (cal-day? (make-cal-day 2023 5 10)))
+    (test-false cal-day?
+		(cal-day? (make-cal-day 2023 2 29)))
+    (test-true cal-day?
+		(cal-day? (make-cal-day 2024 2 29)))
     ))
 
  )