diff --git a/mongo.go b/mongo.go
index 7e381c5..94579c2 100644
--- a/mongo.go
+++ b/mongo.go
@@ -7,11 +7,14 @@ import (
 	"go.mongodb.org/mongo-driver/bson/bsonrw"
 )
 
-func Encoder(encodeContext bsoncodec.EncodeContext, writer bsonrw.ValueWriter, value reflect.Value) error {
+type BsonDecoderEncoder struct {
+}
+
+func (BsonDecoderEncoder) EncodeValue(encodeContext bsoncodec.EncodeContext, writer bsonrw.ValueWriter, value reflect.Value) error {
 	return writer.WriteString(value.Interface().(Decimal).String())
 }
 
-func Decoder(decodeContext bsoncodec.DecodeContext, reader bsonrw.ValueReader, value reflect.Value) error {
+func (BsonDecoderEncoder) DecodeValue(decodeContext bsoncodec.DecodeContext, reader bsonrw.ValueReader, value reflect.Value) error {
 	str, err := reader.ReadString()
 	if err != nil {
 		return err