diff --git a/a_basic_func.go b/a_basic_func.go
index cb89d28..4aee062 100644
--- a/a_basic_func.go
+++ b/a_basic_func.go
@@ -21,7 +21,7 @@ func isInterface(refVal reflect.Value) bool {
 // isString is_string
 func isString(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isString(reflect.ValueOf(refVal.Elem().Interface()))
+		return isString(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.String
 }
@@ -29,7 +29,7 @@ func isString(refVal reflect.Value) bool {
 // isArray is_array
 func isArray(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isArray(reflect.ValueOf(refVal.Elem().Interface()))
+		return isArray(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.Slice || refVal.Kind() == reflect.Array
 }
@@ -37,7 +37,7 @@ func isArray(refVal reflect.Value) bool {
 // isBytes is_bytes
 func isBytes(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isBytes(reflect.ValueOf(refVal.Elem().Interface()))
+		return isBytes(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.Slice && refVal.Type().Elem().Kind() == reflect.Uint8
 }
@@ -45,7 +45,7 @@ func isBytes(refVal reflect.Value) bool {
 // isMap is_map
 func isMap(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isMap(reflect.ValueOf(refVal.Elem().Interface()))
+		return isMap(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.Map
 }
@@ -53,7 +53,7 @@ func isMap(refVal reflect.Value) bool {
 // isStruct is_struct
 func isStruct(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isStruct(reflect.ValueOf(refVal.Elem().Interface()))
+		return isStruct(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.Struct
 }
@@ -61,7 +61,7 @@ func isStruct(refVal reflect.Value) bool {
 // isBoolean is_bool
 func isBoolean(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isBoolean(reflect.ValueOf(refVal.Elem().Interface()))
+		return isBoolean(refVal.Elem())
 	}
 	return refVal.Kind() == reflect.Bool
 
@@ -70,7 +70,7 @@ func isBoolean(refVal reflect.Value) bool {
 // isInt is_int
 func isInt(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isInt(reflect.ValueOf(refVal.Elem().Interface()))
+		return isInt(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
@@ -83,7 +83,7 @@ func isInt(refVal reflect.Value) bool {
 // isInt8 is_int8
 func isInt8(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isInt8(reflect.ValueOf(refVal.Elem().Interface()))
+		return isInt8(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Int8:
@@ -95,7 +95,7 @@ func isInt8(refVal reflect.Value) bool {
 // isInt16 is_int16
 func isInt16(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isInt16(reflect.ValueOf(refVal.Elem().Interface()))
+		return isInt16(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Int16:
@@ -107,7 +107,7 @@ func isInt16(refVal reflect.Value) bool {
 // isInt32 is_int32
 func isInt32(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isInt32(reflect.ValueOf(refVal.Elem().Interface()))
+		return isInt32(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Int32:
@@ -119,7 +119,7 @@ func isInt32(refVal reflect.Value) bool {
 // isInt64 is_int64
 func isInt64(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isInt64(reflect.ValueOf(refVal.Elem().Interface()))
+		return isInt64(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Int64:
@@ -131,7 +131,7 @@ func isInt64(refVal reflect.Value) bool {
 // isUint is_uint
 func isUint(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUint(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUint(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
@@ -141,7 +141,7 @@ func isUint(refVal reflect.Value) bool {
 }
 func isUint8(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUint8(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUint8(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint8:
@@ -153,7 +153,7 @@ func isUint8(refVal reflect.Value) bool {
 // isUint16 is_uint16
 func isUint16(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUint16(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUint16(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint16:
@@ -165,7 +165,7 @@ func isUint16(refVal reflect.Value) bool {
 // isUint32 is_uint32
 func isUint32(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUint32(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUint32(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint32:
@@ -177,7 +177,7 @@ func isUint32(refVal reflect.Value) bool {
 // isUint64 is_uint64
 func isUint64(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUint64(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUint64(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uint64:
@@ -189,7 +189,7 @@ func isUint64(refVal reflect.Value) bool {
 // isUintptr is_uintptr
 func isUintptr(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isUintptr(reflect.ValueOf(refVal.Elem().Interface()))
+		return isUintptr(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Uintptr:
@@ -201,7 +201,7 @@ func isUintptr(refVal reflect.Value) bool {
 // isFloat is_float
 func isFloat(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isFloat(reflect.ValueOf(refVal.Elem().Interface()))
+		return isFloat(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Float32, reflect.Float64:
@@ -213,7 +213,7 @@ func isFloat(refVal reflect.Value) bool {
 // isFloat32 is_float32
 func isFloat32(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isFloat(reflect.ValueOf(refVal.Elem().Interface()))
+		return isFloat(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Float32:
@@ -225,7 +225,7 @@ func isFloat32(refVal reflect.Value) bool {
 // isFloat64 is_float64
 func isFloat64(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isFloat(reflect.ValueOf(refVal.Elem().Interface()))
+		return isFloat(refVal.Elem())
 	}
 	switch refVal.Kind() {
 	case reflect.Float64:
@@ -236,13 +236,16 @@ func isFloat64(refVal reflect.Value) bool {
 
 // isNil is_nil
 func isNil(refVal reflect.Value) bool {
+	if isPtr(refVal) {
+		return isNil(refVal.Elem())
+	}
 	return refVal.Kind() == reflect.Invalid
 }
 
 // isTime is_time
 func isTime(refVal reflect.Value) bool {
 	if isPtr(refVal) {
-		return isTime(reflect.ValueOf(refVal.Elem().Interface()))
+		return isTime(refVal.Elem())
 	}
 	if refVal.Kind() == reflect.Struct {
 		timeType := reflect.TypeOf(time.Time{})
@@ -258,7 +261,7 @@ func isTime(refVal reflect.Value) bool {
 func isNumeric(refVal reflect.Value) bool {
 	switch refVal.Kind() {
 	case reflect.Ptr:
-		return isNumeric(reflect.ValueOf(refVal.Elem().Interface()))
+		return isNumeric(refVal.Elem())
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
 		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 		reflect.Float32, reflect.Float64:
@@ -323,7 +326,7 @@ func toFloat64(refVal reflect.Value) (float64, error) {
 	case reflect.Invalid:
 		return 0, nil
 	case reflect.Ptr:
-		return toFloat64(reflect.ValueOf(refVal.Elem().Interface()))
+		return toFloat64(refVal.Elem())
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
 		return float64(refVal.Uint()), nil
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
@@ -360,7 +363,7 @@ func toBoolean(refVal reflect.Value) (bool, error) {
 	case reflect.Invalid:
 		return false, nil
 	case reflect.Ptr:
-		return toBoolean(reflect.ValueOf(refVal.Elem().Interface()))
+		return toBoolean(refVal.Elem())
 	case reflect.String:
 		// val to lower
 		val = strings.ToLower(refVal.String())
@@ -396,7 +399,7 @@ func toString(refVal reflect.Value) (string, error) {
 	case reflect.Invalid:
 		return "", nil
 	case reflect.Ptr:
-		return toString(reflect.ValueOf(refVal.Elem().Interface()))
+		return toString(refVal.Elem())
 	case reflect.String:
 		return refVal.String(), nil
 	case reflect.Slice:
@@ -431,7 +434,7 @@ func toTime(refVal reflect.Value) (time.Time, error) {
 		return time.Time{}, newError(refVal)
 	}
 	if isPtr(refVal) {
-		return toTime(reflect.ValueOf(refVal.Elem().Interface()))
+		return toTime(refVal.Elem())
 	}
 	var val any
 	val = refVal.Interface()
@@ -449,7 +452,7 @@ func toArray(refVal reflect.Value) ([]any, error) {
 	case reflect.Invalid:
 		return nil, nil
 	case reflect.Ptr:
-		return toArray(reflect.ValueOf(refVal.Elem().Interface()))
+		return toArray(refVal.Elem())
 	case reflect.Slice:
 		if isBytes(refVal) {
 			return toArray(reflect.ValueOf(string(refVal.Bytes())))
@@ -482,7 +485,7 @@ func toMap(refVal reflect.Value) (map[string]any, error) {
 	case reflect.Invalid:
 		return nil, nil
 	case reflect.Ptr:
-		return toMap(reflect.ValueOf(refVal.Elem().Interface()))
+		return toMap(refVal.Elem())
 	case reflect.Slice:
 		if isBytes(refVal) {
 			return toMap(reflect.ValueOf(string(refVal.Bytes())))
diff --git a/serializer_gorm.go b/serializer_gorm.go
index 08bdafe..0d1fad9 100644
--- a/serializer_gorm.go
+++ b/serializer_gorm.go
@@ -46,7 +46,7 @@ func (c *DataRaw) Value(ctx context.Context, field *schema.Field, dst reflect.Va
 	refVal := reflect.ValueOf(fieldValue)
 	switch refVal.Kind() {
 	case reflect.Ptr:
-		return c.Value(ctx, field, dst, refVal.Elem().Interface())
+		return c.Value(ctx, field, dst, refVal.Elem())
 	default:
 		val := refVal.Interface()
 		switch val.(type) {
diff --git a/test/test_int_test.go b/test/test_int_test.go
index d5a807f..acfcc36 100644
--- a/test/test_int_test.go
+++ b/test/test_int_test.go
@@ -130,4 +130,12 @@ func TestParseInt64(t *testing.T) {
 			t.Fatalf("it should be error: %v", err)
 		}
 	})
+	t.Run("NIL", func(t *testing.T) {
+		i := new(int64)
+		i = nil
+		convertedNum, _ := cdt.NewConvert(i).ToInt64E()
+		if convertedNum != 0 {
+			t.Fatalf("return must be 0 instead of %v", convertedNum)
+		}
+	})
 }