diff --git a/mario/mario.hpp b/mario/mario.hpp
index 574f7b6..d04a92a 100644
--- a/mario/mario.hpp
+++ b/mario/mario.hpp
@@ -4,6 +4,7 @@
 #include "../sdlpp/sdlpp_rectrenderer.hpp"
 #include "sprites.hpp"
 #include "blocks.hpp"
+#include <functional>
 
 #define BIG_FLAG 0x0001
 #define FIRE_FLAG 0x0002