diff --git a/lib/visualizers/sp-visualizer-row.h b/lib/visualizers/sp-visualizer-row.h
index 68a30e14..c7f61631 100644
--- a/lib/visualizers/sp-visualizer-row.h
+++ b/lib/visualizers/sp-visualizer-row.h
@@ -56,22 +56,8 @@ struct _SpVisualizerRowClass
   void (*set_reader) (SpVisualizerRow *self,
                       SpCaptureReader *reader);
 
-  gpointer _reserved1;
-  gpointer _reserved2;
-  gpointer _reserved3;
-  gpointer _reserved4;
-  gpointer _reserved5;
-  gpointer _reserved6;
-  gpointer _reserved7;
-  gpointer _reserved8;
-  gpointer _reserved9;
-  gpointer _reserved10;
-  gpointer _reserved11;
-  gpointer _reserved12;
-  gpointer _reserved13;
-  gpointer _reserved14;
-  gpointer _reserved15;
-  gpointer _reserved16;
+  /*< private >*/
+  gpointer _reserved[16];
 };
 
 void           sp_visualizer_row_set_reader       (SpVisualizerRow *self,