diff --git a/src/tree.py b/src/tree.py
index 0412dce1afcfd9db48fe9d220c2b84348d618798..acff1edf9fa14bf701bb9dc28ddd21f8d880d72e 100644
--- a/src/tree.py
+++ b/src/tree.py
@@ -245,7 +245,7 @@ class TreeWalker:
     def ensure_node_id(self, config):
         flag = False
         if "node_id" not in config or \
-                not config["node_id"].startswith(f"{self.tree}-") or \
+                not config["node_id"].startswith(f"{self.name}-") or \
                 config["node_id"] in id_set:
             new_id = self.gen_node_id()
             id_set.add(new_id)