diff --git a/reactos/include/wsahelp.h b/reactos/include/wsahelp.h
index e1e1b4d4297..188a43031a5 100644
--- a/reactos/include/wsahelp.h
+++ b/reactos/include/wsahelp.h
@@ -8,6 +8,7 @@
 #ifndef __WSAHELP_H
 #define __WSAHELP_H
 
+#include <stddef.h>
 #include <winsock2.h>
 
 #ifdef __cplusplus
diff --git a/reactos/lib/packet/include/packet32.h b/reactos/lib/packet/include/packet32.h
index 862cc372555..004a1c9aa46 100644
--- a/reactos/lib/packet/include/packet32.h
+++ b/reactos/lib/packet/include/packet32.h
@@ -33,6 +33,7 @@
 #ifndef __PACKET32
 #define __PACKET32
 
+#include <stddef.h>
 #include <winsock2.h>
 
 // Working modes