diff --git a/proto.go b/proto.go
index 88f6e0b..9d2455c 100644
--- a/proto.go
+++ b/proto.go
@@ -24,7 +24,7 @@ func (c *protoCodec) Marshal(v interface{}) ([]byte, error) {
 	case proto.Message:
 		if nv, nerr := rutil.StructFieldByTag(v, codec.DefaultTagName, flattenTag); nerr == nil {
 			if nm, ok := nv.(proto.Message); ok {
-				return proto.Marshal(nm)
+				m = nm
 			}
 		}
 		return proto.Marshal(m)
@@ -44,7 +44,7 @@ func (c *protoCodec) Unmarshal(d []byte, v interface{}) error {
 	case proto.Message:
 		if nv, nerr := rutil.StructFieldByTag(v, codec.DefaultTagName, flattenTag); nerr == nil {
 			if nm, ok := nv.(proto.Message); ok {
-				return proto.Unmarshal(d, nm)
+				m = nm
 			}
 		}
 		return proto.Unmarshal(d, m)
@@ -78,7 +78,7 @@ func (c *protoCodec) ReadBody(conn io.Reader, v interface{}) error {
 		}
 		if nv, nerr := rutil.StructFieldByTag(v, codec.DefaultTagName, flattenTag); nerr == nil {
 			if nm, ok := nv.(proto.Message); ok {
-				return proto.Unmarshal(buf, nm)
+				m = nm
 			}
 		}
 		return proto.Unmarshal(buf, m)
@@ -94,17 +94,13 @@ func (c *protoCodec) Write(conn io.Writer, m *codec.Message, v interface{}) erro
 		_, err := conn.Write(m.Data)
 		return err
 	case proto.Message:
-		var buf []byte
-		var err error
-
 		if nv, nerr := rutil.StructFieldByTag(v, codec.DefaultTagName, flattenTag); nerr == nil {
 			if nm, ok := nv.(proto.Message); ok {
-				buf, err = proto.Marshal(nm)
+				m = nm
 			}
-		} else {
-			buf, err = proto.Marshal(m)
 		}
 
+		buf, err := proto.Marshal(m)
 		if err != nil {
 			return err
 		} else if len(buf) == 0 {