diff --git a/main.cpp b/main.cpp
index f6e0df3cd1..45c242b0d8 100644
--- a/main.cpp
+++ b/main.cpp
@@ -3,6 +3,10 @@ kwin - the KDE window manager
 
 Copyright (C) 1999, 2000 Matthias Ettrich <ettrich@kde.org>
 ******************************************************************/
+
+// X11/Qt conflict
+#undef Bool
+
 #include <kconfig.h>
 #include "main.h"
 #include "options.h"
diff --git a/plugins.cpp b/plugins.cpp
index 53484c1b34..f58e7b68db 100644
--- a/plugins.cpp
+++ b/plugins.cpp
@@ -9,6 +9,10 @@ Copyright (C) 1999, 2000    Daniel M. Duley <mosfet@kde.org>
 #include <kdesktopfile.h>
 #include <ksimpleconfig.h>
 #include <klocale.h>
+
+// X11/Qt conflict
+#undef Unsorted
+
 #include <qdir.h>
 #include <qfile.h>