diff --git a/src/qabstractseries_p.h b/src/qabstractseries_p.h
index 37fc2b6..4e48c44 100644
--- a/src/qabstractseries_p.h
+++ b/src/qabstractseries_p.h
@@ -48,6 +48,7 @@ class QLegendMarker;
 class ChartTheme;
 class ChartAnimation;
 class ChartItem;
+class BoxPlotChartItem;
 
 class QAbstractSeriesPrivate : public QObject
 {
@@ -78,6 +79,7 @@ Q_SIGNALS:
     void countChanged();
 
 protected:
+    friend class BoxPlotChartItem;
     QAbstractSeries *q_ptr;
     QChart *m_chart;
     QScopedPointer<ChartItem> m_item;
diff --git a/src/qchart.h b/src/qchart.h
index e18b127..8aa6a5b 100644
--- a/src/qchart.h
+++ b/src/qchart.h
@@ -34,6 +34,7 @@ class QAbstractSeries;
 class QAbstractAxis;
 class QLegend;
 class QChartPrivate;
+class QBoxPlotSeries;
 
 class QTCOMMERCIALCHART_EXPORT QChart : public QGraphicsWidget
 {
@@ -141,6 +142,7 @@ protected:
     friend class ChartPresenter;
     friend class ChartThemeManager;
     friend class QAbstractSeries;
+    friend class QBoxPlotSeriesPrivate;
     Q_DISABLE_COPY(QChart)
 };