diff --git a/core.go b/core.go
index b383e6d..4d7a24c 100644
--- a/core.go
+++ b/core.go
@@ -380,6 +380,10 @@ var holidayCache cache
 var holidayCacheLock sync.Mutex
 
 func GetHolidaysDataWithCache() ([]HolidaysItem, error) {
+
+	holidayCacheLock.Lock()
+	defer holidayCacheLock.Unlock()
+
 	if holidayCache.IsExpired() || holidayCache.GetData() == "" {
 		data, err := GetHolidaysData()
 		if err != nil {