diff --git a/sol/console_buffer.hpp b/sol/console_buffer.hpp
index 51383cf..dbb75c9 100644
--- a/sol/console_buffer.hpp
+++ b/sol/console_buffer.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <algorithm>
+#include <cstddef>
 #include <cstdint>
 #include <deque>
 #include <vector>
diff --git a/sol/sol_context.hpp b/sol/sol_context.hpp
index a857c7f..a071892 100644
--- a/sol/sol_context.hpp
+++ b/sol/sol_context.hpp
@@ -5,6 +5,7 @@
 
 #include <boost/asio/io_context.hpp>
 #include <boost/asio/steady_timer.hpp>
+#include <cstddef>
 
 namespace sol
 {
diff --git a/sol/sol_manager.hpp b/sol/sol_manager.hpp
index 6a5887b..74ce8e9 100644
--- a/sol/sol_manager.hpp
+++ b/sol/sol_manager.hpp
@@ -6,6 +6,7 @@
 
 #include <boost/asio/io_context.hpp>
 #include <boost/asio/local/stream_protocol.hpp>
+#include <cstddef>
 #include <map>
 #include <memory>
 #include <string>