diff --git a/src/planarrodassembler.cc b/src/planarrodassembler.cc
index 103dca01c7984e650c805ff2ae019fd99f2603f3..e4ba624333d39238ab66a4c2d1db9812a25182c1 100644
--- a/src/planarrodassembler.cc
+++ b/src/planarrodassembler.cc
@@ -67,7 +67,7 @@ assembleMatrix(const BlockVector<FieldVector<double, blocksize> >& sol,
             = Dune::LagrangeShapeFunctions<double, double, gridDim>::general(it->geometry().type(), elementOrder);
         const int numOfBaseFct = baseSet.size();  
         
-        mat.resize(numOfBaseFct, numOfBaseFct);
+        mat.setSize(numOfBaseFct, numOfBaseFct);
 
         // Extract local solution
         BlockVector<FieldVector<double, blocksize> > localSolution(numOfBaseFct);