diff --git a/src/Projections/FinalPartons.cc b/src/Projections/FinalPartons.cc
--- a/src/Projections/FinalPartons.cc
+++ b/src/Projections/FinalPartons.cc
@@ -1,45 +1,51 @@
 // -*- C++ -*-
 
 #include "Rivet/Projections/FinalPartons.hh"
 #include "Rivet/Tools/RivetHepMC.hh"
 
 namespace Rivet {
 
 
   bool FinalPartons::accept(const Particle& p) const {
 
     // Reject if *not* a parton
     if (!isParton(p))
       return false;
 
     // Accept partons if they end on a standard hadronization vertex
+    #if HEPMC_VERSION_CODE >= 2007000
     if (p.genParticle()->end_vertex() != NULL &&
         p.genParticle()->end_vertex()->id() == 5)
       return true;
+    #else
+    if (p.genParticle()->end_vertex() != NULL &&
+        p.genParticle()->end_vertex()->id() == 5)
+      return true;
+    #endif
 
     // Reject if p has a parton child.
     for (const Particle& c : p.children()) {
       if (isParton(c))
         return false;
     }
 
     // Reject if from a hadron or tau decay.
     if (p.fromDecay())
       return false;
 
     return _cuts->accept(p);
   }
 
 
   void FinalPartons::project(const Event& e) {
     _theParticles.clear();
 
     for (const GenParticlePtr gp : Rivet::particles(e.genEvent())) {
       if (!gp) continue;
       const Particle p(gp);
       if (accept(p)) _theParticles.push_back(p);
     }
   }
 
 
 }