diff --git a/istl/matrixindexset.hh b/istl/matrixindexset.hh
index 97f16fd534e290a1664706fd5a21e4265e6a4a22..0d94ec2cb68e852b59d3920f17117edecb5b7c54 100644
--- a/istl/matrixindexset.hh
+++ b/istl/matrixindexset.hh
@@ -107,6 +107,7 @@ namespace Dune {
 
       matrix.endindices();
 
+      /** \todo This copying could be omitted if there was a resize method for BCRSMatrix */
       m = matrix;
     }