diff --git a/proto.go b/proto.go
index e649574..e3721e4 100644
--- a/proto.go
+++ b/proto.go
@@ -57,6 +57,8 @@ func (c *protoCodec) ReadBody(conn io.Reader, b interface{}) error {
 		buf, err := ioutil.ReadAll(conn)
 		if err != nil {
 			return err
+		} else if buf == nil {
+			return nil
 		}
 		return proto.Unmarshal(buf, m)
 	}