diff --git a/MagickCore/xwindow.c b/MagickCore/xwindow.c
index 0654b65..435496f 100644
--- a/MagickCore/xwindow.c
+++ b/MagickCore/xwindow.c
@@ -62,6 +62,7 @@
 #include "MagickCore/magick.h"
 #include "MagickCore/memory_.h"
 #include "MagickCore/monitor.h"
+#include "MagickCore/nt-base-private.h"
 #include "MagickCore/option.h"
 #include "MagickCore/pixel-accessor.h"
 #include "MagickCore/PreRvIcccm.h"