diff --git a/dune/tectonic/globalnonlinearity.hh b/dune/tectonic/globalnonlinearity.hh
index b8c624928db99bceb6091e2f7b80f4b9785512d2..4ae49881f23487a2144502276c22deb497ac6e98 100644
--- a/dune/tectonic/globalnonlinearity.hh
+++ b/dune/tectonic/globalnonlinearity.hh
@@ -35,7 +35,7 @@ class GlobalNonlinearity {
   void addHessian(VectorType const &v, MatrixType &hessian) const {
     // TODO: is this correct?
     for (size_t i = 0; i < v.size(); ++i) {
-      auto res = restriction(i);
+      auto const res = restriction(i);
       res->addHessian(v[i], hessian[i][i]);
     }
   }
@@ -51,7 +51,7 @@ class GlobalNonlinearity {
     subdifferential[0] = subdifferential[1] = 0;
     for (size_t i = 0; i < u.size(); ++i) {
       Interval<double> D;
-      auto res = restriction(i);
+      auto const res = restriction(i);
       // TODO: is the coordinate system the right one here?
       res->directionalSubDiff(u[i], v[i], D);
       subdifferential[0] += D[0];
@@ -66,13 +66,13 @@ class GlobalNonlinearity {
 
   void addGradient(VectorType const &v, VectorType &gradient) const {
     for (size_t i = 0; i < v.size(); ++i) {
-      auto res = restriction(i);
+      auto const res = restriction(i);
       res->addGradient(v[i], gradient[i]);
     }
   }
 
   double regularity(int i, typename VectorType::block_type const &x) const {
-    auto res = restriction(i);
+    auto const res = restriction(i);
     return res->regularity(x);
   }
 };