diff --git a/cpl/inc/xutility.h b/cpl/inc/xutility.h
index 1705464..cffc850 100644
--- a/cpl/inc/xutility.h
+++ b/cpl/inc/xutility.h
@@ -8,6 +8,9 @@
 #define XUTILITY_H_
 #include "xcore.h"
 
+#include <functional>
+#include <type_traits>
+
 CPL_BEGIN
 
 // The following effectively implements recursive lambdas.