diff -p -up ./src/lightdm-gtk-greeter.c.0001 ./src/lightdm-gtk-greeter.c
--- ./src/lightdm-gtk-greeter.c.0001	2012-08-30 17:39:09.000000000 +0000
+++ ./src/lightdm-gtk-greeter.c	2012-12-20 19:48:38.226379636 +0000
@@ -799,6 +799,8 @@ main (int argc, char **argv)
         background_pixbuf = gdk_pixbuf_new_from_file (path, &error);
         if (!background_pixbuf)
            g_warning ("Failed to load background: %s", error->message);
+        else
+           background_pixbuf = gdk_pixbuf_add_alpha (background_pixbuf, FALSE, 255, 255, 255);
         g_clear_error (&error);
         g_free (path);
     }