diff --git a/tools/vdatatool.cpp b/tools/vdatatool.cpp
index 8d26481cb..987c237d8 100644
--- a/tools/vdatatool.cpp
+++ b/tools/vdatatool.cpp
@@ -23,6 +23,7 @@
 
 VDataTool &VDataTool::operator =(const VDataTool &tool){
    data = tool.getData();
+   _referens = tool.referens();
    return *this;
 }
 
diff --git a/tools/vdatatool.h b/tools/vdatatool.h
index 11749d364..f6c114121 100644
--- a/tools/vdatatool.h
+++ b/tools/vdatatool.h
@@ -24,16 +24,21 @@
 
 #include "container/vcontainer.h"
 
+//We need QObject class because we use qobject_cast.
 class VDataTool : public QObject{
     Q_OBJECT
 public:
-    explicit VDataTool(VContainer *data, QObject *parent = 0): QObject(parent), data(*data){}
+    explicit VDataTool(VContainer *data, QObject *parent = 0): QObject(parent), data(*data), _referens(0){}
     virtual ~VDataTool(){}
     VDataTool& operator= (const VDataTool &tool);
     VContainer getData() const { return data; }
     void setData(const VContainer *value);
+    qint64 referens() const {return _referens;}
+    void incrementReferens(){++_referens;}
+    void decrementReferens(){--_referens;}
 protected:
     VContainer   data;
+    qint64 _referens;
 };
 
 #endif // VDATATOOL_H