diff --git a/mongoext/registry.go b/mongoext/registry.go
index 982102f..36038d7 100644
--- a/mongoext/registry.go
+++ b/mongoext/registry.go
@@ -3,29 +3,20 @@ package mongoext
 import (
 	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/bson/bsoncodec"
-	"go.mongodb.org/mongo-driver/bson/bsonrw"
 	"gogs.mikescher.com/BlackForestBytes/goext/rfctime"
 	"reflect"
 )
 
 func CreateGoExtBsonRegistry() *bsoncodec.Registry {
-	var primitiveCodecs bson.PrimitiveCodecs
-
 	rb := bsoncodec.NewRegistryBuilder()
+
+	rb.RegisterTypeDecoder(reflect.TypeOf(rfctime.RFC3339Time{}), rfctime.RFC3339Time{})
+	rb.RegisterTypeDecoder(reflect.TypeOf(rfctime.RFC3339Time{}), rfctime.RFC3339NanoTime{})
+
 	bsoncodec.DefaultValueEncoders{}.RegisterDefaultEncoders(rb)
 	bsoncodec.DefaultValueDecoders{}.RegisterDefaultDecoders(rb)
 
-	rb.RegisterTypeDecoder(reflect.TypeOf(rfctime.RFC3339Time{}), rfctime.RFC3339Time{})
-
-	primitiveCodecs.RegisterPrimitiveCodecs(rb)
+	bson.PrimitiveCodecs{}.RegisterPrimitiveCodecs(rb)
 
 	return rb.Build()
 }
-
-func encodeRFC3339Time(ec bsoncodec.EncodeContext, vw bsonrw.ValueWriter, val reflect.Value) {
-
-}
-
-func decodeRFC3339Time(ec bsoncodec.EncodeContext, vr bsonrw.ValueReader, val reflect.Value) {
-
-}
diff --git a/rfctime/rfc3339.go b/rfctime/rfc3339.go
index d89419b..33427dd 100644
--- a/rfctime/rfc3339.go
+++ b/rfctime/rfc3339.go
@@ -70,7 +70,10 @@ func (t *RFC3339Time) UnmarshalText(data []byte) error {
 
 func (t *RFC3339Time) UnmarshalBSONValue(bt bsontype.Type, data []byte) error {
 	if bt == bsontype.Null {
-		//t = nil
+		// we can't set nil in UnmarshalBSONValue (so we use default(struct))
+		// https://stackoverflow.com/questions/75167597
+		// https://jira.mongodb.org/browse/GODRIVER-2252
+		*t = RFC3339Time{}
 		return nil
 	}
 	if bt != bsontype.DateTime {
diff --git a/rfctime/rfc3339Nano.go b/rfctime/rfc3339Nano.go
index b6bef36..8868dc8 100644
--- a/rfctime/rfc3339Nano.go
+++ b/rfctime/rfc3339Nano.go
@@ -5,7 +5,10 @@ import (
 	"errors"
 	"fmt"
 	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/bsoncodec"
+	"go.mongodb.org/mongo-driver/bson/bsonrw"
 	"go.mongodb.org/mongo-driver/bson/bsontype"
+	"reflect"
 	"time"
 )
 
@@ -67,7 +70,10 @@ func (t *RFC3339NanoTime) UnmarshalText(data []byte) error {
 
 func (t *RFC3339NanoTime) UnmarshalBSONValue(bt bsontype.Type, data []byte) error {
 	if bt == bsontype.Null {
-		//t = nil
+		// we can't set nil in UnmarshalBSONValue (so we use default(struct))
+		// https://stackoverflow.com/questions/75167597
+		// https://jira.mongodb.org/browse/GODRIVER-2252
+		*t = RFC3339NanoTime{}
 		return nil
 	}
 	if bt != bsontype.DateTime {
@@ -86,6 +92,32 @@ func (t RFC3339NanoTime) MarshalBSONValue() (bsontype.Type, []byte, error) {
 	return bson.MarshalValue(time.Time(t))
 }
 
+func (t RFC3339NanoTime) DecodeValue(dc bsoncodec.DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error {
+	if val.Kind() == reflect.Ptr && val.IsNil() {
+		if !val.CanSet() {
+			return errors.New("ValueUnmarshalerDecodeValue")
+		}
+		val.Set(reflect.New(val.Type().Elem()))
+	}
+
+	tp, src, err := bsonrw.Copier{}.CopyValueToBytes(vr)
+	if err != nil {
+		return err
+	}
+
+	if val.Kind() == reflect.Ptr && len(src) == 0 {
+		val.Set(reflect.Zero(val.Type()))
+		return nil
+	}
+
+	err = t.UnmarshalBSONValue(tp, src)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (t RFC3339NanoTime) Serialize() string {
 	return t.Time().Format(t.FormatStr())
 }