diff --git a/util.go b/util.go
index 4024a9d..bd601bb 100644
--- a/util.go
+++ b/util.go
@@ -161,11 +161,17 @@ func getPrefixForStruct(prefixes []string, fieldStruct *reflect.StructField) []s
 func marshalFile(target interface{}, file string, overWrite bool) error {
 	var f *os.File
 	var err error
+
+	var b []byte
+	if b, err = marshal(target, filepath.Ext(file)); nil != err {
+		return err
+	}
+
 	if Exists(file) {
 		if !overWrite {
 			return fmt.Errorf("Config: File[%s] is exist", file)
 		}
-		if f, err = os.Open(file); nil != err {
+		if f, err = os.OpenFile(file, os.O_WRONLY, os.ModeAppend); nil != err {
 			return err
 		}
 	} else {
@@ -173,11 +179,7 @@ func marshalFile(target interface{}, file string, overWrite bool) error {
 			return err
 		}
 	}
-
-	var b []byte
-	if b, err = marshal(target, filepath.Ext(file)); nil != err {
-		return err
-	}
+	defer f.Close()
 
 	if _, err = f.Write(b); nil != err {
 		return err