diff --git a/src/FitBase/CustomVariableBoxes.h b/src/FitBase/CustomVariableBoxes.h
index 8bb8b41..66e409b 100644
--- a/src/FitBase/CustomVariableBoxes.h
+++ b/src/FitBase/CustomVariableBoxes.h
@@ -1,21 +1,28 @@
 #ifndef CUSTOM_VARIABLES_BOX_H
 #define CUSTOM_VARIABLES_BOX_H
 
 #include "MeasurementVariableBox.h"
 #include "MeasurementVariableBox1D.h"
 #include "MeasurementVariableBox2D.h"
 
 /*!
  *  \addtogroup FitBase
  *  @{
  */
 
 /// Custom box used to also save Q2 for each event.
 class Q2VariableBox1D : public MeasurementVariableBox1D {
 public:
 	inline Q2VariableBox1D() { Reset(); };
 	inline void Reset() {	fQ2 = -999.9; }
+	inline MeasurementVariableBox* CloneSignalBox(){
+          Q2VariableBox1D* box = new Q2VariableBox1D();
+          box->fX = this->fX;
+          box->fSampleWeight = this->fSampleWeight;
+          box->fQ2 = this->fQ2;
+          return box;
+        };
 	double fQ2;
 };
 
 #endif