diff --git a/dune/python/istl/preconditioners.hh b/dune/python/istl/preconditioners.hh
index 566381bae6b02a0bb2514274f6ea802a94987508..547d7308273a3212828de320c3e6997ccc8f88cd 100644
--- a/dune/python/istl/preconditioners.hh
+++ b/dune/python/istl/preconditioners.hh
@@ -51,7 +51,7 @@ namespace Dune
     // -----------------------
 
     template< class X, class Y, class... options >
-    inline void registerPreconditioners ( pybind11::module module, pybind11::class_< LinearOperator< X, Y >, options...  > )
+    inline void registerPreconditioners ( pybind11::module module, pybind11::class_< LinearOperator< X, Y >, options...  > /*cls*/ )
     {
       typedef Dune::Preconditioner< X, Y > Preconditioner;