diff --git a/Kernel_23/include/CGAL/Bbox.h b/Kernel_23/include/CGAL/Bbox.h
index 2bbd0a83b36..803f4c0ffba 100644
--- a/Kernel_23/include/CGAL/Bbox.h
+++ b/Kernel_23/include/CGAL/Bbox.h
@@ -111,7 +111,7 @@ class Bbox
       }
     }
 
-    dilate(int dist)
+    void dilate(int dist)
     {
       using boost::math::float_advance;
       int d = dimension();