diff --git a/Orthtree/include/CGAL/Orthtree.h b/Orthtree/include/CGAL/Orthtree.h
index 0804949b0f1..463954de12a 100644
--- a/Orthtree/include/CGAL/Orthtree.h
+++ b/Orthtree/include/CGAL/Orthtree.h
@@ -392,7 +392,7 @@ public:
       for (int direction = 0; direction < 6; ++direction) {
 
         // Get the neighbor
-        auto neighbor = index(adjacent_node(node, direction));
+        auto neighbor = adjacent_node(node, direction);
 
         // If it doesn't exist, skip it
         if (!neighbor)
@@ -977,8 +977,8 @@ public:
 
   }
 
-  const Node* adjacent_node(Node_index n, typename Node::Local_coordinates direction) const {
-    return adjacent_node(m_nodes[n], direction);
+  boost::optional<Node_index> adjacent_node(Node_index n, typename Node::Local_coordinates direction) const {
+    return {index(adjacent_node(m_nodes[n], direction))};
   }
 
   /*!
@@ -988,10 +988,6 @@ public:
     return adjacent_node(node, std::bitset<Dimension::value>(static_cast<int>(adjacency)));
   }
 
-  const Node* adjacent_node(Node_index n, typename Node::Adjacency adjacency) const {
-    return adjacent_node(m_nodes[n], adjacency);
-  }
-
   /*!
    * \brief equivalent to adjacent_node, except non-const
    */
diff --git a/Orthtree/test/Orthtree/test_node_adjacent.cpp b/Orthtree/test/Orthtree/test_node_adjacent.cpp
index feee130ad7f..0c9cab8821d 100644
--- a/Orthtree/test/Orthtree/test_node_adjacent.cpp
+++ b/Orthtree/test/Orthtree/test_node_adjacent.cpp
@@ -42,39 +42,47 @@ int main(void) {
   std::cout << octree << std::endl;
 
   // Root node should have no siblings
-  assert(octree.adjacent_node(octree.root(), 0) == nullptr);
-  assert(octree.adjacent_node(octree.root(), 1) == nullptr);
-  assert(octree.adjacent_node(octree.root(), 2) == nullptr);
-  assert(octree.adjacent_node(octree.root(), 3) == nullptr);
-  assert(octree.adjacent_node(octree.root(), 4) == nullptr);
-  assert(octree.adjacent_node(octree.root(), 5) == nullptr);
+  assert(!octree.adjacent_node(octree.index(octree.root()), 0));
+  assert(!octree.adjacent_node(octree.index(octree.root()), 1));
+  assert(!octree.adjacent_node(octree.index(octree.root()), 2));
+  assert(!octree.adjacent_node(octree.index(octree.root()), 3));
+  assert(!octree.adjacent_node(octree.index(octree.root()), 4));
+  assert(!octree.adjacent_node(octree.index(octree.root()), 5));
 
   // Left Top Front node should have siblings to the Right, Down, and Back
-  auto left_top_back = octree.children(octree.root())[Traits::LEFT_TOP_BACK];
+  auto left_top_back = octree.index(octree.children(octree.root())[Traits::LEFT_TOP_BACK]);
 
-  assert(&octree.children(octree.root())[Traits::RIGHT_TOP_BACK] == octree.adjacent_node(left_top_back, Traits::RIGHT));
+  assert(octree.index(&octree.children(octree.root())[Traits::RIGHT_TOP_BACK]) ==
+         octree.adjacent_node(left_top_back, Traits::RIGHT));
   assert(
-    &octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK] == octree.adjacent_node(left_top_back, Traits::DOWN));
-  assert(&octree.children(octree.root())[Traits::LEFT_TOP_FRONT] == octree.adjacent_node(left_top_back, Traits::FRONT));
-  assert(octree.adjacent_node(left_top_back, Traits::LEFT) == nullptr);
-  assert(octree.adjacent_node(left_top_back, Traits::UP) == nullptr);
-  assert(octree.adjacent_node(left_top_back, Traits::BACK) == nullptr);
+    octree.index(&octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK]) ==
+    octree.adjacent_node(left_top_back, Traits::DOWN));
+  assert(octree.index(&octree.children(octree.root())[Traits::LEFT_TOP_FRONT]) ==
+         octree.adjacent_node(left_top_back, Traits::FRONT));
+  assert(!octree.adjacent_node(left_top_back, Traits::LEFT));
+  assert(!octree.adjacent_node(left_top_back, Traits::UP));
+  assert(!octree.adjacent_node(left_top_back, Traits::BACK));
 
   std::cout << octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK] << std::endl;
 
   auto right_top_back_of_left_bottom_back =
-    octree.children(octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK])[Traits::RIGHT_TOP_BACK];
-  assert(&octree.children(octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK])[Traits::LEFT_TOP_BACK] ==
-         octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::LEFT));
-  assert(&octree.children(octree.root())[Traits::RIGHT_BOTTOM_BACK] ==
-         octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::RIGHT));
-  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::RIGHT) != nullptr);
-  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::UP) != nullptr);
-  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::DOWN) != nullptr);
-  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::FRONT) != nullptr);
+    octree.index(octree.children(octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK])[Traits::RIGHT_TOP_BACK]);
+
+  assert(
+    octree.index(&octree.children(octree.children(octree.root())[Traits::LEFT_BOTTOM_BACK])[Traits::LEFT_TOP_BACK]) ==
+    octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::LEFT)
+  );
+  assert(
+    octree.index(&octree.children(octree.root())[Traits::RIGHT_BOTTOM_BACK]) ==
+    octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::RIGHT)
+  );
+  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::RIGHT).has_value());
+  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::UP).has_value());
+  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::DOWN).has_value());
+  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::FRONT).has_value());
 
   // A node at the back of the tree should have no neighbor to its back
-  assert(octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::BACK) == nullptr);
+  assert(!octree.adjacent_node(right_top_back_of_left_bottom_back, Traits::BACK));
 
   return 0;
 }