From f5461a9f98e514cbf1226b28f642bcb2438e6b0f Mon Sep 17 00:00:00 2001
From: Dave <54906029+davemilller@users.noreply.github.com>
Date: Thu, 7 Dec 2023 15:45:11 -0700
Subject: [PATCH] month first weekday bug (#628)

---
 scheduler.go      | 2 +-
 scheduler_test.go | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/scheduler.go b/scheduler.go
index f51e0bd..e681fbe 100644
--- a/scheduler.go
+++ b/scheduler.go
@@ -828,7 +828,7 @@ func (s *Scheduler) MonthFirstWeekday(weekday time.Weekday) *Scheduler {
 		return s.Cron(fmt.Sprintf("0 0 %d %d %d", day, month, weekday))
 	}
 
-	return s.Cron(fmt.Sprintf("0 0 %d %d %d", day, month+1, weekday))
+	return s.Cron(fmt.Sprintf("0 0 %d %d %d", day, (month+1)%12, weekday))
 }
 
 // LimitRunsTo limits the number of executions of this job to n.
diff --git a/scheduler_test.go b/scheduler_test.go
index 9edfbd8..14485a5 100644
--- a/scheduler_test.go
+++ b/scheduler_test.go
@@ -2263,6 +2263,11 @@ func TestScheduler_EveryMonthFirstWeekday(t *testing.T) {
 			expected: time.Date(2022, time.March, 7, 0, 0, 0, 0, time.UTC),
 			weekday:  time.Monday,
 		},
+		{
+			current:  time.Date(2022, time.December, 7, 0, 0, 0, 0, time.UTC),
+			expected: time.Date(2023, time.January, 2, 0, 0, 0, 0, time.UTC),
+			weekday:  time.Monday,
+		},
 	}
 
 	for _, tc := range testCases {