diff --git a/dune/tectonic/globalruinanonlinearity.hh b/dune/tectonic/globalruinanonlinearity.hh
index 4397aa341d59caa0be6ff9366a2a51d56eb5a39c..cc85463123e2ffca3231cdb67247698d800a7779 100644
--- a/dune/tectonic/globalruinanonlinearity.hh
+++ b/dune/tectonic/globalruinanonlinearity.hh
@@ -3,6 +3,7 @@
 
 #include <vector>
 
+#include <dune/common/nullptr.hh>
 #include <dune/common/fmatrix.hh>
 #include <dune/common/fvector.hh>
 #include <dune/istl/bcrsmatrix.hh>
@@ -45,7 +46,7 @@ class GlobalRuinaNonlinearity
     if ((*nodalIntegrals)[i][0] == 0)
       return trivialNonlinearity;
 
-    if (restrictions[i] != NULL)
+    if (restrictions[i] != nullptr)
       return restrictions[i];
 
     auto const func = make_shared<RuinaFunction const>(
diff --git a/dune/tectonic/myblockproblem.hh b/dune/tectonic/myblockproblem.hh
index 8498bf00721e5acfe1fae6a598b546824e2e2136..97091a4537ab5717ee631fd9faacc3d5b5926e1a 100644
--- a/dune/tectonic/myblockproblem.hh
+++ b/dune/tectonic/myblockproblem.hh
@@ -4,6 +4,7 @@
 #define MY_BLOCK_PROBLEM_HH
 
 #include <dune/common/bitsetvector.hh>
+#include <dune/common/nullptr.hh>
 #include <dune/common/parametertree.hh>
 
 #include <dune/solvers/common/staticmatrixtools.hh>
@@ -242,7 +243,7 @@ class MyBlockProblem<MyConvexProblemTypeTEMPLATE>::IterateObject {
           assert(false);
       }
 
-      LocalMatrixType const *localA = NULL;
+      LocalMatrixType const *localA = nullptr;
       LocalVectorType localb(problem.f[m]);
 
       typename MatrixType::row_type::ConstIterator it;
@@ -254,7 +255,7 @@ class MyBlockProblem<MyConvexProblemTypeTEMPLATE>::IterateObject {
         else
           it->mmv(u[j], localb); // localb -= A[m][j] * u[j]
       }
-      assert(localA != NULL);
+      assert(localA != nullptr);
 
       auto const phi = problem.phi.restriction(m);
       Dune::SampleFunctional<block_size> localJ(*localA, localb, phi,