diff --git a/private/windowshadows.cpp b/private/windowshadows.cpp
index 10964f312..450a0db25 100644
--- a/private/windowshadows.cpp
+++ b/private/windowshadows.cpp
@@ -21,6 +21,8 @@
 #include <QWidget>
 #include <QPainter>
 
+#include <config.h>
+
 #if HAVE_X11
 #include <QX11Info>
 #include <X11/Xatom.h>