diff --git a/AABB_tree/include/CGAL/AABB_tree.h b/AABB_tree/include/CGAL/AABB_tree.h
index dda850e3538..0fe6f6bf5de 100644
--- a/AABB_tree/include/CGAL/AABB_tree.h
+++ b/AABB_tree/include/CGAL/AABB_tree.h
@@ -603,7 +603,7 @@ public:
     std::atomic<bool> m_atomic_search_tree_constructed;
 #else
     bool m_need_build = false;
-    bool m_search_tree_constructed = false;
+    mutable bool m_search_tree_constructed = false;
 #endif
 
   private:
diff --git a/Polygon_mesh_processing/include/CGAL/Side_of_triangle_mesh.h b/Polygon_mesh_processing/include/CGAL/Side_of_triangle_mesh.h
index 416f3638a80..f2ea731ec1a 100644
--- a/Polygon_mesh_processing/include/CGAL/Side_of_triangle_mesh.h
+++ b/Polygon_mesh_processing/include/CGAL/Side_of_triangle_mesh.h
@@ -187,7 +187,7 @@ public:
 #ifdef CGAL_HAS_THREADS
       delete atomic_tree_ptr.load();
 #else
-      delete tree_ptr.get();
+      delete tree_ptr;
 #endif
   }