diff --git a/v2/cal_business.go b/v2/cal_business.go
index 6a49afa..161eaa9 100644
--- a/v2/cal_business.go
+++ b/v2/cal_business.go
@@ -128,11 +128,16 @@ func (c *BusinessCalendar) IsWorkTime(date time.Time) bool {
 	}
 
 	h, m, s := date.Clock()
-	return (h == startHour && m == startMinute && s >= startSecond) ||
-		(h == startHour && m > startMinute) ||
-		(h > startHour && h < endHour) ||
-		(h == endHour && m < endMinute) ||
-		(h == endHour && m == endMinute && s <= endSecond)
+
+	timeOfDateCalculator := func(hour, minute, second int) time.Duration {
+		return time.Duration(hour)*time.Hour + time.Duration(minute)*time.Minute + time.Duration(second)*time.Second
+	}
+
+	timeOfDate := timeOfDateCalculator(h, m, s)
+	startTimeOfDate := timeOfDateCalculator(startHour, startMinute, startSecond)
+	endTimeOfDate := timeOfDateCalculator(endHour, endMinute, endSecond)
+
+	return timeOfDate >= startTimeOfDate && timeOfDate <= endTimeOfDate
 }
 
 // WorkdaysRemain reports the total number of remaining workdays in the month
diff --git a/v2/cal_business_test.go b/v2/cal_business_test.go
index 0f10c42..c11227d 100644
--- a/v2/cal_business_test.go
+++ b/v2/cal_business_test.go
@@ -116,6 +116,13 @@ func TestIsWorkTime(t *testing.T) {
 	cal3.SetWorkday(time.Friday, true)
 	cal3.SetWorkHours(6*time.Hour, 24*time.Hour)
 
+	cal3.WorkdayStartFunc = func(date time.Time) time.Time {
+		return time.Date(date.Year(), date.Month(), date.Day(), date.Day()%12, 30, 0, 0, time.UTC)
+	}
+	cal3.WorkdayEndFunc = func(date time.Time) time.Time {
+		return time.Date(date.Year(), date.Month(), date.Day(), date.Day()%12, 45, 0, 0, time.UTC)
+	}
+
 	tests := []struct {
 		c    *BusinessCalendar
 		d    time.Time
@@ -131,6 +138,11 @@ func TestIsWorkTime(t *testing.T) {
 		{cal2, dt(2020, 4, 1, 7, 00), true},
 		{cal2, dt(2020, 4, 1, 7, 50), false},
 
+		{cal3, dt(2020, 4, 1, 1, 30), true},
+		{cal3, dt(2020, 4, 1, 0, 00), false},
+		{cal3, dt(2020, 4, 1, 1, 35), true},
+		{cal3, dt(2020, 4, 1, 1, 45), true},
+		{cal3, dt(2020, 4, 1, 1, 46), false},
 		{cal3, dt(2023, 10, 19, 23, 59), true},
 		{cal3, dt(2023, 10, 20, 0, 0), false},
 	}