diff --git a/xo-arena/include/xo/arena/hashmap/DArenaHashMapUtil.hpp b/xo-arena/include/xo/arena/hashmap/DArenaHashMapUtil.hpp
index 689559c7..403ff61d 100644
--- a/xo-arena/include/xo/arena/hashmap/DArenaHashMapUtil.hpp
+++ b/xo-arena/include/xo/arena/hashmap/DArenaHashMapUtil.hpp
@@ -3,6 +3,10 @@
  *  @author Roland Conybeare, Jan 2026
  **/
 
+#pragma once
+
+#include <cstdint>
+
 namespace xo {
     namespace mm {
         /** @class DArenaHashMapUtil