diff --git a/Voronoi_diagram_2/include/CGAL/Voronoi_diagram_2/Cached_degeneracy_testers.h b/Voronoi_diagram_2/include/CGAL/Voronoi_diagram_2/Cached_degeneracy_testers.h
index 904831073f8..60c5021933e 100644
--- a/Voronoi_diagram_2/include/CGAL/Voronoi_diagram_2/Cached_degeneracy_testers.h
+++ b/Voronoi_diagram_2/include/CGAL/Voronoi_diagram_2/Cached_degeneracy_testers.h
@@ -328,7 +328,7 @@ public:
     vmap.clear();
   }
 
-  void swap(Self& other) {
+  void swap(Self& /* other */) {
     // doing a real swap is not ready yet
 #if 1
     clear();