diff --git a/dune/solvers/iterationsteps/multigridstep.hh b/dune/solvers/iterationsteps/multigridstep.hh
index 6dbd016161c22c996567136e30097c8f8db58494..ac18ac10a2d0db21a2e322d2b2f36959423af4df 100644
--- a/dune/solvers/iterationsteps/multigridstep.hh
+++ b/dune/solvers/iterationsteps/multigridstep.hh
@@ -140,6 +140,9 @@
             mat_[level_] = &mat;
             x_[level_]   = x;
             rhs_[level_] = rhs;
+
+            // Preprocess must be called again, to create the new matrix hierarchy
+            preprocessCalled = false;
         }
 
         template <class DerivedTransferHierarchy>