diff --git a/src/Vector/vector_dist_cell_list_tests.hpp b/src/Vector/vector_dist_cell_list_tests.hpp
index e831f21ec1ec8379cec754827014fa982694457f..099173f2d9f9a826a567435ecf917656ae95e659 100644
--- a/src/Vector/vector_dist_cell_list_tests.hpp
+++ b/src/Vector/vector_dist_cell_list_tests.hpp
@@ -573,7 +573,7 @@ BOOST_AUTO_TEST_CASE( vector_dist_symmetric_verlet_list )
 		size_t id;
 		Point<3,float> xq;
 
-		bool operator<(const struct point_and_gid & pag)
+		bool operator<(const struct point_and_gid & pag) const
 		{
 			return (id < pag.id);
 		}