diff --git a/src/piechart/qpieseries.cpp b/src/piechart/qpieseries.cpp
index b0466f4..f874507 100644
--- a/src/piechart/qpieseries.cpp
+++ b/src/piechart/qpieseries.cpp
@@ -330,7 +330,7 @@ void QPieSeries::remove(QPieSlice* slice)
     emit removed(QList<QPieSlice*>() << slice);
 
     delete slice;
-    slice = NULL;
+    slice = 0;
 }
 
 /*!
@@ -651,7 +651,7 @@ bool QPieSeries::setModel(QAbstractItemModel* model)
     }
     else
     {
-        m_model = NULL;
+        m_model = 0;
         return false;
     }
 }
@@ -660,7 +660,7 @@ void QPieSeries::setModelMapping(int modelValuesLine, int modelLabelsLine, Qt::O
 {
     Q_D(QPieSeries);
 
-    if (m_model == NULL)
+    if (m_model == 0)
         return;
 
     d->m_mapValues = modelValuesLine;
diff --git a/src/qseries.h b/src/qseries.h
index 7434616..e48529e 100644
--- a/src/qseries.h
+++ b/src/qseries.h
@@ -44,7 +44,7 @@ public:
     };
 
 protected:
-    QSeries(QObject *parent = 0) : QObject(parent) {m_model = NULL;}
+    QSeries(QObject *parent = 0) : QObject(parent) {m_model = 0;}
 
 public:
     virtual ~QSeries() {}