diff --git a/bmcweb_config.h.in b/bmcweb_config.h.in
index 394cfdf..2e880fc 100644
--- a/bmcweb_config.h.in
+++ b/bmcweb_config.h.in
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdint>
+#include <cstddef>
 
 // clang-format off
 constexpr const int bmcwebInsecureDisableXssPrevention =