diff --git a/include/xo/unit/xquantity_iostream.hpp b/include/xo/unit/xquantity_iostream.hpp
index 0eb6ce9..6b57990 100644
--- a/include/xo/unit/xquantity_iostream.hpp
+++ b/include/xo/unit/xquantity_iostream.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include "Quantity.hpp"
+#include "xquantity.hpp"
 #include "natural_unit_iostream.hpp"
 //#include <iostream>