diff --git a/AK/Atomic.h b/AK/Atomic.h
index 0ab0b19601..5c53e23449 100644
--- a/AK/Atomic.h
+++ b/AK/Atomic.h
@@ -1,5 +1,9 @@
 #pragma once
 
+#ifndef KERNEL
+#include <stddef.h>
+#endif
+
 namespace AK {
 
 enum MemoryOrder