diff --git a/AABB_tree/examples/AABB_tree/AABB_cached_bbox_example.cpp b/AABB_tree/examples/AABB_tree/AABB_cached_bbox_example.cpp
index cf07b245cba..1dc1acdc2c8 100644
--- a/AABB_tree/examples/AABB_tree/AABB_cached_bbox_example.cpp
+++ b/AABB_tree/examples/AABB_tree/AABB_cached_bbox_example.cpp
@@ -48,7 +48,7 @@ Bbox_3 bbox(boost::graph_traits<Surface_mesh>::face_descriptor fd,
 }
 
 
-void surface_mesh_cache_bbox(char* fname)
+void surface_mesh_cache_bbox(const char* fname)
 {
   typedef boost::graph_traits<Surface_mesh>::face_descriptor face_descriptor;
   typedef Surface_mesh::Property_map<face_descriptor,Bbox_3> Bbox_pmap;