diff --git a/refs/marshal.go b/refs/marshal.go
index dc8517f..ef85324 100644
--- a/refs/marshal.go
+++ b/refs/marshal.go
@@ -118,11 +118,11 @@ func (o *ObjectID) StableSize() int {
 func ObjectIDNestedListMarshal(fNum int64, buf []byte, ids []ObjectID) (off int) {
 	prefix, _ := proto.NestedStructurePrefix(fNum)
 	for i := range ids {
-		off += binary.PutUvarint(buf, prefix)
+		off += binary.PutUvarint(buf[off:], prefix)
 
 		n := ids[i].StableSize()
 		off += binary.PutUvarint(buf[off:], uint64(n))
-		off += proto.BytesMarshal(objectIDValField, buf, ids[i].val)
+		off += proto.BytesMarshal(objectIDValField, buf[off:], ids[i].val)
 	}
 
 	return
diff --git a/rpc/message/test/message.go b/rpc/message/test/message.go
index e3ce9cd..7c4450f 100644
--- a/rpc/message/test/message.go
+++ b/rpc/message/test/message.go
@@ -16,7 +16,7 @@ type jsonMessage interface {
 }
 
 type binaryMessage interface {
-	StableMarshal([]byte) ([]byte, error)
+	StableMarshal([]byte) []byte
 	Unmarshal([]byte) error
 }
 
@@ -54,8 +54,7 @@ func TestRPCMessage(t *testing.T, msgGens ...func(empty bool) message.Message) {
 
 			if bm, ok := msg.(binaryMessage); ok {
 				t.Run(fmt.Sprintf("Binary_%T", msg), func(t *testing.T) {
-					data, err := bm.StableMarshal(nil)
-					require.NoError(t, err)
+					data := bm.StableMarshal(nil)
 
 					bm2 := msgGen(true).(binaryMessage)
 					require.NoError(t, bm2.Unmarshal(data))