diff --git a/include/itemtypes.hpp b/include/itemtypes.hpp
index e61e8e8d..1be49326 100644
--- a/include/itemtypes.hpp
+++ b/include/itemtypes.hpp
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <unordered_map>
+#include <boost/unordered/unordered_flat_map.hpp>
 #include <string>
 #include <vector>