diff --git a/Tracking/TrkVertexFitter/TrkV0Fitter/TrkV0Fitter/TrkV0VertexFitter.h b/Tracking/TrkVertexFitter/TrkV0Fitter/TrkV0Fitter/TrkV0VertexFitter.h
index 27046f04a09cc2cd568eb3b15e5630f79ccb702d..d32fec23c6c955d72ce2dee61c07b9a8d242ff2a 100755
--- a/Tracking/TrkVertexFitter/TrkV0Fitter/TrkV0Fitter/TrkV0VertexFitter.h
+++ b/Tracking/TrkVertexFitter/TrkV0Fitter/TrkV0Fitter/TrkV0VertexFitter.h
@@ -158,13 +158,13 @@ namespace Trk
     */
       
     virtual xAOD::Vertex * fit(const std::vector<const xAOD::TrackParticle*> & vectorTrk,
-                               const std::vector<double> masses,
+                               const std::vector<double>& masses,
                                const double& constraintMass,
                                const xAOD::Vertex* pointingVertex,
                                const Amg::Vector3D& startingPoint) const;
 
     virtual xAOD::Vertex * fit(const std::vector<const Trk::TrackParameters*> & perigeeList,
-                               const std::vector<double> masses,
+                               const std::vector<double>& masses,
                                const double& constraintMass,
                                const xAOD::Vertex* pointingVertex,
                                const Amg::Vector3D& startingPoint) const;
diff --git a/Tracking/TrkVertexFitter/TrkV0Fitter/src/TrkV0VertexFitter.cxx b/Tracking/TrkVertexFitter/TrkV0Fitter/src/TrkV0VertexFitter.cxx
index ca1fdb73ee50881f0d1d069c7aeac85be0fa459d..0704ab2ffda553a83c24e62ead2bc0bdd0ba62f0 100755
--- a/Tracking/TrkVertexFitter/TrkV0Fitter/src/TrkV0VertexFitter.cxx
+++ b/Tracking/TrkVertexFitter/TrkV0Fitter/src/TrkV0VertexFitter.cxx
@@ -116,7 +116,7 @@ namespace Trk
 
   /** Interface for xAOD::TrackParticle with mass and pointing constraints */
   xAOD::Vertex * TrkV0VertexFitter::fit(const std::vector<const xAOD::TrackParticle*> & vectorTrk,
-                                        const std::vector<double> masses,
+                                        const std::vector<double>& masses,
                                         const double& constraintMass,
                                         const xAOD::Vertex* pointingVertex,
                                         const Amg::Vector3D& firstStartingPoint) const
@@ -210,7 +210,7 @@ namespace Trk
 
   /** Interface for Trk::TrackParameters with mass and pointing constraints */
   xAOD::Vertex * TrkV0VertexFitter::fit(const std::vector<const Trk::TrackParameters*>& originalPerigees,
-                                        const std::vector<double> masses,
+                                        const std::vector<double>& masses,
                                         const double& constraintMass,
                                         const xAOD::Vertex* pointingVertex,
                                         const Amg::Vector3D& firstStartingPoint) const