diff --git a/gtsam/inference/BayesTree.h b/gtsam/inference/BayesTree.h
index 7391e9a10..34e5c0c45 100644
--- a/gtsam/inference/BayesTree.h
+++ b/gtsam/inference/BayesTree.h
@@ -202,7 +202,7 @@ namespace gtsam {
 		}
 
     /** return nodes */
-    Nodes nodes() const { return nodes_; }
+    const Nodes& nodes() const { return nodes_; }
 
 		/** return root clique */
 		const sharedClique& root() const { return root_;	}