diff --git a/COMPOSITE_TODO b/COMPOSITE_TODO
index 0659378611..8312334471 100644
--- a/COMPOSITE_TODO
+++ b/COMPOSITE_TODO
@@ -150,8 +150,6 @@ OpenGL TODO
 XRender TODO
 ==============================
 
-+ SceneXrender::Window::performPaint() doesn't use brightness
-
 + SceneXrender::paintTransformedScreen() doesn't handle properly extending of painted area
     in window's pre-paint - see the transformedShape() comment
     - and currently seems to be generally broken
diff --git a/scene_xrender.cpp b/scene_xrender.cpp
index 6c9614708b..097155ea51 100644
--- a/scene_xrender.cpp
+++ b/scene_xrender.cpp
@@ -516,12 +516,18 @@ void SceneXrender::Window::performPaint( int mask, QRegion region, WindowPaintDa
             {
             XRenderComposite( display(), PictOpSrc, pic, None, buffer, 0, 0, 0, 0,
                 x, y, width, height);
+            // fake brightness change by overlaying black
+            XRenderColor col = { 0, 0, 0, 0xffff * ( 1 - data.brightness ) };
+            XRenderFillRectangle( display(), PictOpOver, buffer, &col, x, y, width, height );
             }
         else
             {
             Picture alpha = alphaMask( data.opacity );
             XRenderComposite( display(), PictOpOver, pic, alpha, buffer, 0, 0, 0, 0,
                 x, y, width, height);
+            // fake brightness change by overlaying black
+            XRenderColor col = { 0, 0, 0, 0xffff * ( 1 - data.brightness ) * data.opacity };
+            XRenderFillRectangle( display(), PictOpOver, buffer, &col, x, y, width, height );
             transformed_shape = QRegion();
             }
         }