diff --git a/dune/istl/paamg/parameters.hh b/dune/istl/paamg/parameters.hh
index d2b630de02ddcefd3691d449c0a33863b49d11ca..edff1ef89b69bdf37eef814f08134dd449a3bce4 100644
--- a/dune/istl/paamg/parameters.hh
+++ b/dune/istl/paamg/parameters.hh
@@ -394,6 +394,7 @@ namespace Dune
        * @brief Set the debugging level.
        *
        * @param level If 0 no debugging output will be generated.
+       * @warning In parallel the level has to be consistent over all procceses.
        */
       void setDebugLevel(int level)
       {