diff --git a/map/simple_tree.hpp b/map/simple_tree.hpp
index 4afeb4d272..ae9c474ff8 100644
--- a/map/simple_tree.hpp
+++ b/map/simple_tree.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "../std/vector.hpp"
+#include "../std/algorithm.hpp"
 
 template <class T>
 class SimpleTree