diff --git a/src/barchart/qbarset.cpp b/src/barchart/qbarset.cpp
index 4d96079..06b16f9 100644
--- a/src/barchart/qbarset.cpp
+++ b/src/barchart/qbarset.cpp
@@ -265,7 +265,7 @@ void QBarSet::append(const QPointF value)
     Appends a list of \a values to set. Works like append with single point.
     \sa append()
 */
-void QBarSet::append(const QList<QPointF> values)
+void QBarSet::append(const QList<QPointF> &values)
 {
     int index = d_ptr->m_values.count();
     d_ptr->append(values);
@@ -287,7 +287,7 @@ void QBarSet::append(const qreal value)
     are converted to QPointF, where x coordinate is the index of point and y coordinate is the value.
     \sa append()
 */
-void QBarSet::append(const QList<qreal> values)
+void QBarSet::append(const QList<qreal> &values)
 {
     int index = d_ptr->m_values.count();
     d_ptr->append(values);
diff --git a/src/barchart/qbarset.h b/src/barchart/qbarset.h
index c91c1f0..6f49844 100644
--- a/src/barchart/qbarset.h
+++ b/src/barchart/qbarset.h
@@ -49,9 +49,9 @@ public:
     QString label() const;
 
     void append(const QPointF value);
-    void append(const QList<QPointF> values);
+    void append(const QList<QPointF> &values);
     void append(const qreal value);
-    void append(const QList<qreal> values);
+    void append(const QList<qreal> &values);
 
     QBarSet& operator << (const qreal &value);
     QBarSet& operator << (const QPointF &value);