diff --git a/src/mcts.rs b/src/mcts.rs
index 37e2133..bd50edf 100644
--- a/src/mcts.rs
+++ b/src/mcts.rs
@@ -97,7 +97,7 @@ impl<'conf, S: GameState + std::fmt::Debug> MCTS<'conf, S> {
 
     /// MCTS Phase 2: Expansion - Expand the selected node on the tree
     fn expand(&mut self, id: usize) {
-        let parent: &Node<S> = self.arena.get_node_mut(id);
+        let parent: &Node<S> = self.arena.get_node(id);
         let legal_actions: Vec<S::Action> = parent.state.get_legal_actions();
         let parent_state: S = parent.state.clone();
         for action in legal_actions {