diff --git a/dune/solvers/operators/nulloperator.hh b/dune/solvers/operators/nulloperator.hh
index 4ab35a4ce7474e1e38f05f46ae0c01d3dc57090d..b58a1d958d4ea09a3fd250803b78060a8fecccb5 100644
--- a/dune/solvers/operators/nulloperator.hh
+++ b/dune/solvers/operators/nulloperator.hh
@@ -50,8 +50,8 @@ class NullOperator
          *
          *  This is here to allow for NullOperator as block_type (this is needed in the constructor of RowDummy)
          */
-        template <class T>
-        NullOperator(const T& t){}
+//        template <class T>
+//        NullOperator(const T& t){}
 
         /** \brief Matrix-Vector multiplication
          *