C++11: override keyword

Source : http://en.cppreference.com/w/cpp/language/override
diff --git a/include/json/reader.h b/include/json/reader.h
index c07ce19..9a8a4e3 100644
--- a/include/json/reader.h
+++ b/include/json/reader.h
@@ -333,9 +333,9 @@
   Json::Value settings_;
 
   CharReaderBuilder();
-  virtual ~CharReaderBuilder();
+  ~CharReaderBuilder() override;
 
-  virtual CharReader* newCharReader() const;
+  CharReader* newCharReader() const override;
 
   /** \return true if 'settings' are legal and consistent;
    *   otherwise, indicate bad settings via 'invalid'.