diff --git a/Helicity/Vertex/AbstractFFFFVertex.h b/Helicity/Vertex/AbstractFFFFVertex.h
--- a/Helicity/Vertex/AbstractFFFFVertex.h
+++ b/Helicity/Vertex/AbstractFFFFVertex.h
@@ -1,73 +1,73 @@
 // -*- C++ -*-
 #ifndef Helicity_AbstractFFFFVertex_H
 #define Helicity_AbstractFFFFVertex_H
 //
 // This is the declaration of the AbstractFFFFVertex class.
 //
 
 #include "VertexBase.h"
 #include "ThePEG/Helicity/WaveFunction/SpinorWaveFunction.h"
 #include "ThePEG/Helicity/WaveFunction/SpinorBarWaveFunction.h"
 #include "AbstractFFFFVertex.fh"
 
 namespace ThePEG {
 namespace Helicity {
 
 /**
  * The AbstractFFFFVertex class provides a base class for all 4-fermion vertices
  * in ThePEG
  */
 class AbstractFFFFVertex: public VertexBase {
 
 public:
 
   /**
    * The default constructor.
    */
   AbstractFFFFVertex() : VertexBase(VertexType::FFFF) {}
 
   /**
    * Members to calculate the helicity amplitude expressions for vertices
    * and off-shell particles.
    */
   //@{
   /**
    * Evalulate the vertex.
    * @param q2 The scale \f$q^2\f$ for the coupling at the vertex.
    * @param sp1   The wavefunction for the first ferimon.
    * @param sp2   The wavefunction for the second ferimon.
    * @param sbar1 The wavefunction for the first antifermion.
    * @param sbar2 The wavefunction for the second antifermion.
    */
   virtual Complex evaluate(Energy2 q2,
 			   const SpinorWaveFunction & sp1,
+			   const SpinorBarWaveFunction & sbar1,
 			   const SpinorWaveFunction & sp2,
-			   const SpinorBarWaveFunction & sbar1,
 			   const SpinorBarWaveFunction & sbar2) = 0;
   //@}
 
 public:
 
   /**
    * The standard Init function used to initialize the interfaces.
    * Called exactly once for each class by the class description system
    * before the main function starts or
    * when this class is dynamically loaded.
    */
   static void Init();
   
 private:
 
   /**
    * The assignment operator is private and must never be called.
    * In fact, it should not even be implemented.
    */
   AbstractFFFFVertex & operator=(const AbstractFFFFVertex &);
 
 };
 
 }
 }
 
 
 #endif /* Helicity_AbstractFFFFVertex_H */