diff --git a/Event/PhysEvent/include/Event/Particle.h b/Event/PhysEvent/include/Event/Particle.h
index 1304dd8d01d6a7e3bb79c36b7f9637bafe30ab78..df523ad379fb9b8095c192eb3dc10e53c1826c3b 100644
--- a/Event/PhysEvent/include/Event/Particle.h
+++ b/Event/PhysEvent/include/Event/Particle.h
@@ -823,3 +823,6 @@ inline Gaudi::XYZVector LHCb::Particle::slopes() const {
   return Gaudi::XYZVector( fabs( m_momentum.Z() ) > 0 ? m_momentum.X() / m_momentum.Z() : 0,
                            fabs( m_momentum.Z() ) > 0 ? m_momentum.Y() / m_momentum.Z() : 0, 1.0 );
 }
+
+// Including forward declarations
+REGISTER_HEADER( LHCb::Particle, "Event/Particle.h" );