diff --git a/composite.cpp b/composite.cpp
index 1c4b530cac..f594d1b2c7 100644
--- a/composite.cpp
+++ b/composite.cpp
@@ -69,9 +69,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #ifdef HAVE_XCOMPOSITE
 #include <X11/extensions/Xcomposite.h>
-#if XCOMPOSITE_MAJOR > 0 || XCOMPOSITE_MINOR >= 3
-#define HAVE_XCOMPOSITE_OVERLAY
-#endif
 #endif
 #ifdef HAVE_XRANDR
 #include <X11/extensions/Xrandr.h>
diff --git a/overlaywindow.cpp b/overlaywindow.cpp
index 89fa65c74e..65db6dc591 100644
--- a/overlaywindow.cpp
+++ b/overlaywindow.cpp
@@ -18,6 +18,8 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 
+#include <config-X11.h>
+
 #include "overlaywindow.h"
 
 #include "kwinglobals.h"
@@ -28,6 +30,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <X11/extensions/shape.h>
 
+#ifdef HAVE_XCOMPOSITE
+#include <X11/extensions/Xcomposite.h>
+#if XCOMPOSITE_MAJOR > 0 || XCOMPOSITE_MINOR >= 3
+#define HAVE_XCOMPOSITE_OVERLAY
+#endif
+#endif
+
 namespace KWin {
 OverlayWindow::OverlayWindow()
     : m_window(None)
@@ -48,10 +57,10 @@ bool OverlayWindow::create()
     if (!Extensions::shapeInputAvailable())  // needed in setupOverlay()
         return false;
 #ifdef HAVE_XCOMPOSITE_OVERLAY
-    m_overlay = XCompositeGetOverlayWindow(display(), rootWindow());
-    if (m_overlay == None)
+    m_window = XCompositeGetOverlayWindow(display(), rootWindow());
+    if (m_window == None)
         return false;
-    XResizeWindow(display(), m_overlay, displayWidth(), displayHeight());
+    XResizeWindow(display(), m_window, displayWidth(), displayHeight());
     return true;
 #else
     return false;
@@ -132,7 +141,7 @@ void OverlayWindow::destroy()
     XShapeCombineRectangles(display(), m_window, ShapeBounding, 0, 0, &rec, 1, ShapeSet, Unsorted);
     XShapeCombineRectangles(display(), m_window, ShapeInput, 0, 0, &rec, 1, ShapeSet, Unsorted);
 #ifdef HAVE_XCOMPOSITE_OVERLAY
-    XCompositeReleaseOverlayWindow(display(), m_overlay);
+    XCompositeReleaseOverlayWindow(display(), m_window);
 #endif
     m_window = None;
     m_shown = false;