diff --git a/modules/installer/cd-dvd/installation-cd-graphical.nix b/modules/installer/cd-dvd/installation-cd-graphical.nix
index a3c533bb715..bda613a2532 100644
--- a/modules/installer/cd-dvd/installation-cd-graphical.nix
+++ b/modules/installer/cd-dvd/installation-cd-graphical.nix
@@ -1,11 +1,20 @@
 # This module defines a NixOS installation CD that contains X11 and
 # KDE 4.
 
-{config, pkgs, ...}:
+{ config, pkgs, ... }:
 
 {
   require = [
     ./installation-cd-base.nix
     ../../profiles/graphical.nix
   ];
+
+  # Disable compositing for now.  It seems to cause problems with KDE
+  # 4.5 on some graphics drivers (such as Cirrus and VGA in QEMU).
+  services.xserver.config =
+    ''
+      Section "Extensions"
+        Option "Composite" "Disable"
+      EndSection
+    '';
 }