Fix a warning.

diff --git a/coupled_laplace_problem/coupled_laplace_problem.cc b/coupled_laplace_problem/coupled_laplace_problem.cc
index 072e67a155835c21893d55cfb4c7d5e594fa1277..e295a18b27ee6fbb2f4a5936131575d8403a5b6b 100644 (file)
--- a/coupled_laplace_problem/coupled_laplace_problem.cc
+++ b/coupled_laplace_problem/coupled_laplace_problem.cc
@@ -423,7 +423,7 @@ CoupledLaplaceProblem<dim>::make_grid()
   triangulation.refine_global(4);
 
   for (const auto &cell : triangulation.active_cell_iterators())
-    for (const auto face : cell->face_iterators())
+    for (const auto &face : cell->face_iterators())
       {
         // We choose the boundary in positive x direction for the
         // interface coupling.