diff --git a/trees/segtree_generic.cc b/trees/segtree_generic.cc
index 63a22f2..0e8ceee 100644
--- a/trees/segtree_generic.cc
+++ b/trees/segtree_generic.cc
@@ -98,7 +98,7 @@ public:
         return res;
     }
 
-    const vector<info_type> get_d() {
+    const vector<info_type>& get_d() {
         return d;
     }
 };