diff --git a/scripts/kconfig/qconf.cc b/scripts/kconfig/qconf.cc
index df274febb3e5..1500c38f0cca 100644
--- a/scripts/kconfig/qconf.cc
+++ b/scripts/kconfig/qconf.cc
@@ -6,6 +6,7 @@
 #include <qglobal.h>
 
 #if QT_VERSION < 0x040000
+#include <stddef.h>
 #include <qmainwindow.h>
 #include <qvbox.h>
 #include <qvaluelist.h>