diff --git a/net/packet/util.go b/net/packet/util.go
index 6fe3163..6f6f619 100644
--- a/net/packet/util.go
+++ b/net/packet/util.go
@@ -25,6 +25,9 @@ type Ary struct {
 
 func (a Ary) WriteTo(r io.Writer) (n int64, err error) {
 	array := reflect.ValueOf(a.Ary)
+	for array.Kind() == reflect.Ptr {
+		array = array.Elem()
+	}
 	for i := 0; i < array.Len(); i++ {
 		elem := array.Index(i)
 		nn, err := elem.Interface().(FieldEncoder).WriteTo(r)
@@ -54,7 +57,13 @@ func (a Ary) length() int {
 
 func (a Ary) ReadFrom(r io.Reader) (n int64, err error) {
 	length := a.length()
-	array := reflect.ValueOf(a.Ary).Elem()
+	array := reflect.ValueOf(a.Ary)
+	for array.Kind() == reflect.Ptr {
+		array = array.Elem()
+	}
+	if !array.CanAddr() {
+		panic(errors.New("the Ary is not addressable"))
+	}
 	if array.Cap() < length {
 		array.Set(reflect.MakeSlice(array.Type(), length, length))
 	}
diff --git a/net/packet/util_test.go b/net/packet/util_test.go
index 03ea4dc..0d0f8d2 100644
--- a/net/packet/util_test.go
+++ b/net/packet/util_test.go
@@ -93,6 +93,24 @@ func TestAry_WriteTo(t *testing.T) {
 	}
 }
 
+func TestAry_WriteTo_pointer(t *testing.T) {
+	var buf bytes.Buffer
+	want := []byte{
+		0x00, 0x00, 0x00, 0x01,
+		0x00, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x03,
+	}
+	data := pk.Ary{Ary: &[]pk.Int{1, 2, 3}}
+
+	_, err := data.WriteTo(&buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(buf.Bytes(), want) {
+		t.Fatalf("Ary encoding error: got %#v, want %#v", buf.Bytes(), want)
+	}
+}
+
 func ExampleOpt_ReadFrom() {
 	var has pk.Boolean