diff --git a/util/inc/leatherman/util/scope_exit.hpp b/util/inc/leatherman/util/scope_exit.hpp
index 3aed675..54d2d29 100644
--- a/util/inc/leatherman/util/scope_exit.hpp
+++ b/util/inc/leatherman/util/scope_exit.hpp
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <functional>
+#include <cstddef>
 
 namespace leatherman { namespace util {
 
diff --git a/util/inc/leatherman/util/scoped_resource.hpp b/util/inc/leatherman/util/scoped_resource.hpp
index 2ff19fc..7bce075 100644
--- a/util/inc/leatherman/util/scoped_resource.hpp
+++ b/util/inc/leatherman/util/scoped_resource.hpp
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <functional>
+#include <cstddef>
 
 namespace leatherman { namespace util {
     /**