diff --git a/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/flip_edges.h b/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/flip_edges.h
index 7153fd93bfb..f849baea079 100644
--- a/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/flip_edges.h
+++ b/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/flip_edges.h
@@ -1177,7 +1177,7 @@ std::size_t flip_all_edges(const std::vector<VertexPair>& edges,
     boost::optional<boost::container::small_vector<Cell_handle, 64> > > inc_cells;
 
   std::size_t count = 0;
-  for (const VertexPair vp : edges)
+  for (const VertexPair& vp : edges)
   {
     boost::optional<boost::container::small_vector<Cell_handle, 64>>&
       o_inc_vh = inc_cells[vp.first];
diff --git a/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/smooth_vertices.h b/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/smooth_vertices.h
index f0e71dfefa1..1d94ef35e1d 100644
--- a/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/smooth_vertices.h
+++ b/Tetrahedral_remeshing/include/CGAL/Tetrahedral_remeshing/internal/smooth_vertices.h
@@ -543,7 +543,7 @@ public:
           const Vector_3 current_pos(CGAL::ORIGIN, point(v->point()));
 
           const std::vector<Surface_patch_index>& v_surface_indices = vertices_surface_indices[v];
-          for (const Surface_patch_index si : v_surface_indices)
+          for (const Surface_patch_index& si : v_surface_indices)
           {
             //Check if the mls surface exists to avoid degenerated cases