diff --git a/cache_test.go b/cache_test.go
index 1dd2252..a3e762e 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -7,6 +7,11 @@ import (
 
 func Test_cache_IsExpired(t *testing.T) {
 	cachet := cache{}
+
+	if !cachet.IsExpired() {
+		t.Error("cache should be expired")
+	}
+
 	if cachet.IsExpired() {
 		cachet.SetData("hello", time.Second*5)
 	}
diff --git a/core.go b/core.go
index 22687aa..110af5a 100644
--- a/core.go
+++ b/core.go
@@ -380,8 +380,6 @@ var holidayCache *cache
 var holidayCacheLock sync.Mutex
 
 func GetHolidaysDataWithCache() ([]HolidaysItem, error) {
-	holidayCacheLock.Lock()
-	defer holidayCacheLock.Unlock()
 	if holidayCache.IsExpired() {
 		data, err := GetHolidaysData()
 		if err != nil {
@@ -392,9 +390,6 @@ func GetHolidaysDataWithCache() ([]HolidaysItem, error) {
 	data := holidayCache.GetData()
 	var result []HolidaysItem
 	err := json.Unmarshal([]byte(data), &result)
-	if len(data) == 0 {
-		panic("GetHolidaysDataWithCache json unmarshal error")
-	}
 	return result, err
 }