diff --git a/rod3d.cc b/rod3d.cc
index 7626f6be119ab2b090b475c9593361c8bb7c168a..2a015cf184ed3960b47793fe5af2e037d18b1eb2 100644
--- a/rod3d.cc
+++ b/rod3d.cc
@@ -189,7 +189,8 @@ int main (int argc, char *argv[]) try
     MatrixIndexSet indices(exactSolution.size(), exactSolution.size());
     rodAssembler.getNeighborsPerVertex(indices);
     indices.exportIdx(hessian);
-    rodAssembler.assembleMatrix(exactSolution, hessian);
+    BlockVector<FieldVector<double,6> > dummyRhs(x.size());
+    rodAssembler.assembleGradientAndHessian(exactSolution, dummyRhs, hessian);
 
 
     double error = std::numeric_limits<double>::max();