diff --git a/map/src/map.hpp b/map/src/map.hpp
index 32a4a52..9a39ea1 100644
--- a/map/src/map.hpp
+++ b/map/src/map.hpp
@@ -570,6 +570,7 @@ class map {
   map() : node_count(0), tree_root(nullptr) {}
   map(const map &other) {
     node_count = other.node_count;
+    tree_root = nullptr;
     RedBlackTreeNodeType::CopyFrom(tree_root, other.tree_root);
   }
   map(map &&other) {