diff --git a/src/qt/win_cdrom_ioctl.c b/src/qt/win_cdrom_ioctl.c
index f89ec7412..7e3a588c3 100644
--- a/src/qt/win_cdrom_ioctl.c
+++ b/src/qt/win_cdrom_ioctl.c
@@ -26,6 +26,7 @@
 #include "ntddcdrm.h"
 #include "ntddscsi.h"
 #include <stdarg.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>