diff --git a/src/piechart/qpiemodelmapper.cpp b/src/piechart/qpiemodelmapper.cpp
index 2de1a54..39f7c24 100644
--- a/src/piechart/qpiemodelmapper.cpp
+++ b/src/piechart/qpiemodelmapper.cpp
@@ -301,6 +301,9 @@ void QPieModelMapperPrivate::sliceValueChanged()
 
 void QPieModelMapperPrivate::modelUpdated(QModelIndex topLeft, QModelIndex bottomRight)
 {
+    if (m_model == 0 || m_series == 0)
+        return;
+
     if (m_modelSignalsBlock)
         return;