diff --git a/dumux/adaptive/markelements.hh b/dumux/adaptive/markelements.hh
index 0f992bbb13e5c2d5ecce88471354d72ba234683b..abde8522daf22340e8c52872ca8f15c021661a23 100644
--- a/dumux/adaptive/markelements.hh
+++ b/dumux/adaptive/markelements.hh
@@ -37,7 +37,7 @@ namespace Dumux {
  * \return bool whether or not anything has been marked
  */
 template<class Grid, class Indicator>
-bool markElements(Grid& grid, Indicator& indicator, bool verbose = true)
+bool markElements(Grid& grid, const Indicator& indicator, bool verbose = true)
 {
     // mark elements according to indicator
     std::size_t refine = 0;