diff --git a/dune/tectonic/myblockproblem.hh b/dune/tectonic/myblockproblem.hh
index a620f471e40dab9453370f1996dffd96a9ab5df4..8498bf00721e5acfe1fae6a598b546824e2e2136 100644
--- a/dune/tectonic/myblockproblem.hh
+++ b/dune/tectonic/myblockproblem.hh
@@ -256,7 +256,7 @@ class MyBlockProblem<MyConvexProblemTypeTEMPLATE>::IterateObject {
       }
       assert(localA != NULL);
 
-      auto phi = problem.phi.restriction(m);
+      auto const phi = problem.phi.restriction(m);
       Dune::SampleFunctional<block_size> localJ(*localA, localb, phi,
                                                 ignore_component);