diff --git a/internal/defs/types.go b/internal/defs/types.go
index 7e230ef..5002e99 100644
--- a/internal/defs/types.go
+++ b/internal/defs/types.go
@@ -127,6 +127,17 @@ func (self *Type) Tag() Tag {
 	}
 }
 
+func (self *Type) IsEnum() bool {
+	switch self.T {
+	case T_enum:
+		return true
+	case T_pointer:
+		return self.V.IsEnum()
+	default:
+		return false
+	}
+}
+
 func (self *Type) Free() {
 	typePool.Put(self)
 }
diff --git a/internal/defs/types_test.go b/internal/defs/types_test.go
index 7ac67d2..a2c4a2d 100644
--- a/internal/defs/types_test.go
+++ b/internal/defs/types_test.go
@@ -37,3 +37,25 @@ func TestTypes_MapKeyType(t *testing.T) {
 	require.NoError(t, err)
 	fmt.Println(tt)
 }
+
+func TestTypes_Enum(t *testing.T) {
+	type EnumType int64
+	type Int32 int32
+	type StructWithEnum struct {
+		A EnumType  `frugal:"1,optional,EnumType"`
+		B *EnumType `frugal:"2,optional,EnumType"`
+		C Int32     `frugal:"3,optional,Int32"`
+		D int64     `frugal:"4,optional,i64"`
+	}
+	ff, err := DoResolveFields(reflect.TypeOf(StructWithEnum{}))
+	require.NoError(t, err)
+	require.Len(t, ff, 4)
+	require.True(t, ff[0].Type.IsEnum())
+	require.Equal(t, ff[0].Type.T, T_enum)
+	require.True(t, ff[1].Type.IsEnum())
+	require.Equal(t, ff[1].Type.T, T_pointer)
+	require.Equal(t, ff[1].Type.V.T, T_enum)
+	require.False(t, ff[2].Type.IsEnum())
+	require.False(t, ff[3].Type.IsEnum())
+
+}
diff --git a/internal/reflect/decoder_test.go b/internal/reflect/decoder_test.go
index 070b962..12ebb63 100644
--- a/internal/reflect/decoder_test.go
+++ b/internal/reflect/decoder_test.go
@@ -27,9 +27,11 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestDecode(t *testing.T) {
+func init() {
 	rand.Seed(time.Now().Unix())
+}
 
+func TestDecode(t *testing.T) {
 	type testcase struct {
 		name   string
 		update func(p *TestTypes)
@@ -197,6 +199,108 @@ func TestDecode(t *testing.T) {
 	}
 }
 
+func TestDecodeOptional(t *testing.T) {
+	type testcase struct {
+		name   string
+		update func(p *TestTypesOptional)
+		test   func(t *testing.T, p1 *TestTypesOptional)
+	}
+
+	var (
+		vInt16   = int16(rand.Uint32() & 0xffff)
+		vInt32   = int32(rand.Uint32())
+		vInt64   = int64(rand.Uint64())
+		vFloat64 = math.Float64frombits(rand.Uint64())
+		vTrue    = true
+		vString  = "hello"
+		vByte    = int8(0x55)
+		vEnum    = Numberz(int32(rand.Uint32()))
+	)
+
+	for math.IsNaN(vFloat64) { // fix test failure
+		vFloat64 = math.Float64frombits(rand.Uint64())
+	}
+
+	testcases := []testcase{
+		{
+			name:   "case_bool",
+			update: func(p0 *TestTypesOptional) { p0.FBool = &vTrue },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vTrue, *p1.FBool) },
+		},
+		{
+			name:   "case_string",
+			update: func(p0 *TestTypesOptional) { p0.String_ = &vString },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vString, *p1.String_) },
+		},
+		{
+			name:   "case_byte",
+			update: func(p0 *TestTypesOptional) { p0.FByte = &vByte },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vByte, *p1.FByte) },
+		},
+		{
+			name:   "case_int8",
+			update: func(p0 *TestTypesOptional) { p0.I8 = &vByte },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vByte, *p1.I8) },
+		},
+		{
+			name:   "case_int16",
+			update: func(p0 *TestTypesOptional) { p0.I16 = &vInt16 },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vInt16, *p1.I16) },
+		},
+		{
+			name:   "case_int32",
+			update: func(p0 *TestTypesOptional) { p0.I32 = &vInt32 },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vInt32, *p1.I32) },
+		},
+		{
+			name:   "case_int64",
+			update: func(p0 *TestTypesOptional) { p0.I64 = &vInt64 },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vInt64, *p1.I64) },
+		},
+		{
+			name:   "case_float64",
+			update: func(p0 *TestTypesOptional) { p0.Double = &vFloat64 },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vFloat64, *p1.Double) },
+		},
+		{
+			name:   "case_enum",
+			update: func(p0 *TestTypesOptional) { p0.Enum = &vEnum },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vEnum, *p1.Enum) },
+		},
+		{
+			name:   "case_typedef",
+			update: func(p0 *TestTypesOptional) { p0.UID = &vInt64 },
+			test:   func(t *testing.T, p1 *TestTypesOptional) { assert.Equal(t, vInt64, *p1.UID) },
+		},
+	}
+	for _, tc := range testcases {
+		name := tc.name
+		updatef := tc.update
+		testf := tc.test
+		t.Run(name, func(t *testing.T) {
+			p0 := NewTestTypesOptional()
+			updatef(p0) // update by testcase func
+
+			b := make([]byte, EncodedSize(p0))
+			n, err := Encode(b, p0)
+			require.NoError(t, err)
+			require.Equal(t, len(b), n)
+
+			// verify by gopkg thrift
+			n, err = thrift.Binary.Skip(b, thrift.TType(tSTRUCT))
+			require.NoError(t, err)
+			require.Equal(t, n, len(b))
+
+			p1 := &TestTypesOptional{}
+			n, err = Decode(b, p1)
+			require.NoError(t, err)
+			require.Equal(t, len(b), n)
+
+			testf(t, p1) // test by testcase func
+		})
+	}
+}
+
 func TestDecodeRequired(t *testing.T) {
 	type S0 struct {
 		V *bool `frugal:"1,optional,bool"`
diff --git a/internal/reflect/ttype.go b/internal/reflect/ttype.go
index 05ba667..b8abeeb 100644
--- a/internal/reflect/ttype.go
+++ b/internal/reflect/ttype.go
@@ -160,7 +160,7 @@ func newTType(x *defs.Type) *tType {
 	t.T = ttype(x.Tag())
 	t.WT = t.T
 	t.Tag = x.T
-	if t.Tag == defs.T_enum {
+	if x.IsEnum() {
 		t.T = tENUM
 	}
 	t.RT = x.S