diff --git a/copasi/plotUI/CQCustomPlot.h b/copasi/plotUI/CQCustomPlot.h
index 0148626b2a..6aca1d3df1 100644
--- a/copasi/plotUI/CQCustomPlot.h
+++ b/copasi/plotUI/CQCustomPlot.h
@@ -351,6 +351,7 @@ private slots:
   QCPLayoutGrid * mpSubLayout;
 
   bool mHaveNewData;
+  QScrollBar * mpScrollbar;
   QLineEdit * mpMaxLegend;
   QLabel * mpPosLabel;