diff --git a/cvte.go b/cvte.go
index 6a0d63f..2665a45 100644
--- a/cvte.go
+++ b/cvte.go
@@ -73,8 +73,13 @@ func indirect(a interface{}) (val interface{}, rt reflect.Type, rv reflect.Value
 	val = rv.Interface()
 
 	switch rt.Kind() {
-	case reflect.Ptr: // indirect the base type, if is be referenced many times
-		for rv.Kind() == reflect.Ptr && !rv.IsNil() {
+	case reflect.Ptr: // indirect the base type, if is been referenced many times
+		for rv.Kind() == reflect.Ptr {
+			// stop indirect until nil, avoid stack overflow
+			if rv.IsNil() {
+				val = nil
+				return
+			}
 			rv = rv.Elem()
 		}
 		return indirect(rv.Interface())
diff --git a/cvte_test.go b/cvte_test.go
index 73ee5ad..076851d 100644
--- a/cvte_test.go
+++ b/cvte_test.go
@@ -14,29 +14,28 @@ import (
 
 // indirect type
 type (
-	AliasTypeBool    bool
-	AliasTypeInt     int
-	AliasTypeInt8    int8
-	AliasTypeInt16   int16
-	AliasTypeInt32   int32
-	AliasTypeInt64   int64
-	AliasTypeUint    uint
-	AliasTypeUint8   uint8
-	AliasTypeUint16  uint16
-	AliasTypeUint32  uint32
-	AliasTypeUint64  uint64
-	AliasTypeFloat32 float32
-	AliasTypeFloat64 float64
-	AliasTypeString  string
-	AliasTypeBytes   []byte
+	AliasTypeBool      bool
+	AliasTypeInt       int
+	AliasTypeInt8      int8
+	AliasTypeInt16     int16
+	AliasTypeInt32     int32
+	AliasTypeInt64     int64
+	AliasTypeUint      uint
+	AliasTypeUint8     uint8
+	AliasTypeUint16    uint16
+	AliasTypeUint32    uint32
+	AliasTypeUint64    uint64
+	AliasTypeFloat32   float32
+	AliasTypeFloat64   float64
+	AliasTypeString    string
+	AliasTypeBytes     []byte
+	AliasTypeInterface interface{}
 )
 
 var (
 	aliasTypeBool_true  AliasTypeBool = true
 	aliasTypeBool_false AliasTypeBool = false
-)
 
-var (
 	aliasTypeInt_0 AliasTypeInt = 0
 	aliasTypeInt_1 AliasTypeInt = 1
 
@@ -49,6 +48,10 @@ var (
 	aliasTypeString_8d15_minus AliasTypeString = "-8.15"
 	aliasTypeString_on         AliasTypeString = "on"
 	aliasTypeString_off        AliasTypeString = "off"
+
+	pointerRunes       = []rune("中国")
+	pointerInterNil    *AliasTypeInterface
+	AliasTypeBytes_nil AliasTypeBytes
 )
 
 // custom type
diff --git a/int.go b/int.go
index 62613eb..83bc636 100644
--- a/int.go
+++ b/int.go
@@ -332,6 +332,8 @@ func convUint64(val interface{}) (uint64, error) {
 	// indirect type
 	v, _, rv := indirect(val)
 	switch vv := v.(type) {
+	case nil:
+		return 0, nil
 	case bool:
 		if vv {
 			return 1, nil
@@ -423,6 +425,8 @@ func convInt64(val interface{}) (int64, error) {
 	// indirect type
 	v, _, rv := indirect(val)
 	switch vv := v.(type) {
+	case nil:
+		return 0, nil
 	case bool:
 		if vv {
 			return 1, nil
diff --git a/int_test.go b/int_test.go
index a9d21df..80af942 100644
--- a/int_test.go
+++ b/int_test.go
@@ -1017,6 +1017,7 @@ func TestUint64E(t *testing.T) {
 		{AliasTypeBytes("0"), 0, false},
 		{AliasTypeBytes("10.98"), 10, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{int(-8), 0, true},
@@ -1129,6 +1130,7 @@ func TestUint32E(t *testing.T) {
 		{AliasTypeBytes("0"), 0, false},
 		{AliasTypeBytes("10.98"), 10, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{int(-8), 0, true},
@@ -1242,6 +1244,7 @@ func TestUint16E(t *testing.T) {
 		{AliasTypeBytes("0"), 0, false},
 		{AliasTypeBytes("10.98"), 10, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{int(-8), 0, true},
@@ -1357,6 +1360,7 @@ func TestUint8E(t *testing.T) {
 		{AliasTypeBytes("0"), 0, false},
 		{AliasTypeBytes("10.98"), 10, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{int(-8), 0, true},
@@ -1474,6 +1478,7 @@ func TestUintE(t *testing.T) {
 		{AliasTypeBytes("0"), 0, false},
 		{AliasTypeBytes("10.98"), 10, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{int(-8), 0, true},
@@ -1607,6 +1612,7 @@ func TestInt64E(t *testing.T) {
 		{aliasTypeBool_false, 0, false},
 		{&aliasTypeBool_false, 0, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{"10a", 0, true},
@@ -1724,6 +1730,7 @@ func TestInt32E(t *testing.T) {
 		{aliasTypeBool_false, 0, false},
 		{&aliasTypeBool_false, 0, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{"10a", 0, true},
@@ -1842,6 +1849,7 @@ func TestInt16E(t *testing.T) {
 		{aliasTypeBool_false, 0, false},
 		{&aliasTypeBool_false, 0, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{"10a", 0, true},
@@ -1962,6 +1970,7 @@ func TestInt8E(t *testing.T) {
 		{aliasTypeBool_false, 0, false},
 		{&aliasTypeBool_false, 0, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{"10a", 0, true},
@@ -2083,6 +2092,7 @@ func TestIntE(t *testing.T) {
 		{aliasTypeBool_false, 0, false},
 		{&aliasTypeBool_false, 0, false},
 		{json.Number("1"), 1, false},
+		{pointerInterNil, 0, false},
 
 		// errors
 		{"10a", 0, true},