diff --git a/include/behaviortree_cpp_v3/tree_node.h b/include/behaviortree_cpp_v3/tree_node.h
index 7d94f6eb3..272a89742 100644
--- a/include/behaviortree_cpp_v3/tree_node.h
+++ b/include/behaviortree_cpp_v3/tree_node.h
@@ -153,7 +153,7 @@ class TreeNode
     friend class BehaviorTreeFactory;
     friend class DecoratorNode;
     friend class ControlNode;
-    friend class Tree;
+    friend struct Tree;
 
     // Only BehaviorTreeFactory should call this
     void setRegistrationID(StringView ID)