diff --git a/src/ObjCommon/Utils/DistinctMapper.h b/src/ObjCommon/Utils/DistinctMapper.h
index 46d616c4..a5173285 100644
--- a/src/ObjCommon/Utils/DistinctMapper.h
+++ b/src/ObjCommon/Utils/DistinctMapper.h
@@ -2,6 +2,7 @@
 
 #include "Utils/ClassUtils.h"
 
+#include <cstddef>
 #include <map>
 #include <vector>
 
diff --git a/src/Utils/Math/Vector.h b/src/Utils/Math/Vector.h
index 3657d33d..2a188a1d 100644
--- a/src/Utils/Math/Vector.h
+++ b/src/Utils/Math/Vector.h
@@ -2,6 +2,7 @@
 #include "Utils/ClassUtils.h"
 
 #include <cassert>
+#include <cstddef>
 
 template<typename T> class Vector2
 {
diff --git a/src/ZoneLoading/Loading/IHashProvider.h b/src/ZoneLoading/Loading/IHashProvider.h
index 27d8562c..da76becb 100644
--- a/src/ZoneLoading/Loading/IHashProvider.h
+++ b/src/ZoneLoading/Loading/IHashProvider.h
@@ -1,4 +1,6 @@
 #pragma once
+
+#include <cstddef>
 #include <cstdint>
 
 class IHashProvider