diff --git a/constant.go b/constant.go
new file mode 100644
index 0000000..5780d6f
--- /dev/null
+++ b/constant.go
@@ -0,0 +1,6 @@
+package fcm
+
+const (
+	logDBName        = "log_fcm"
+	maxTokensPerSend = 1000
+)
diff --git a/helper.go b/helper.go
index 5836c63..c823526 100644
--- a/helper.go
+++ b/helper.go
@@ -6,11 +6,6 @@ import (
 	"github.com/thoas/go-funk"
 )
 
-const (
-	logDBName        = "fcm"
-	maxTokensPerSend = 1000
-)
-
 // base64Decode ...
 func base64Decode(text string) []byte {
 	sDec, _ := b64.StdEncoding.DecodeString(text)
diff --git a/log.go b/log.go
index 37adbc6..81adeb7 100644
--- a/log.go
+++ b/log.go
@@ -35,7 +35,7 @@ func (s Service) saveLog(doc Log) {
 
 	// Assign data
 	doc.ID = mongodb.NewObjectID()
-	doc.CreatedAt = Now()
+	doc.CreatedAt = now()
 
 	if _, err := s.DB.Collection(logDBName).InsertOne(ctx, doc); err != nil {
 		pretty.Println("*** FCM create log error", err.Error())
diff --git a/time.go b/time.go
index 0d2bfdd..ab69cd6 100644
--- a/time.go
+++ b/time.go
@@ -10,14 +10,13 @@ import "time"
 
 const timezoneHCM = "Asia/Ho_Chi_Minh"
 
-// GetHCMLocation ...
-func GetHCMLocation() *time.Location {
+// getHCMLocation ...
+func getHCMLocation() *time.Location {
 	l, _ := time.LoadLocation(timezoneHCM)
 	return l
 }
 
-
-// Now ...
-func Now() time.Time {
-	return time.Now().In(GetHCMLocation())
+// now ...
+func now() time.Time {
+	return time.Now().In(getHCMLocation())
 }