diff --git a/playground/charts/StackedChart.cpp b/playground/charts/StackedChart.cpp
index 4d7bf219..91aedf7c 100644
--- a/playground/charts/StackedChart.cpp
+++ b/playground/charts/StackedChart.cpp
@@ -79,6 +79,7 @@ void StackedChart::setSeries( const QVector< ChartSample >& samples )
     {
         // caching the cumulated values
 
+        m_data->cumulatedValues.clear();
         m_data->cumulatedValues.reserve( samples.size() );
 
         qreal total = 0.0;