diff --git a/dune/istl/solvers.hh b/dune/istl/solvers.hh
index d19e05978db054012d217078887478a82984a1f1..5055a124fca4c73b2ff7cc96e4f2fc6536228f5b 100644
--- a/dune/istl/solvers.hh
+++ b/dune/istl/solvers.hh
@@ -1301,8 +1301,8 @@ namespace Dune {
 
     static void
     update(X &x, int k,
-           std::vector< std::vector<field_type> > & h,
-           std::vector<field_type> & s, std::vector<F> v)
+           const std::vector< std::vector<field_type> > & h,
+           const std::vector<field_type> & s, const std::vector<F> &v)
     {
       std::vector<field_type> y(s);