--- a/ccdemos/spheres_shadow.cc	Sun Nov 25 17:58:29 2007 +0100
+++ b/ccdemos/spheres_shadow.cc	Sun Nov 25 21:47:10 2007 +0100
@@ -4,6 +4,8 @@
 int main()
 {
 	Raytracer rt;
+	rt.setThreads(1);
+
 	Light light1(Vector3(0.0, 5.0, 5.0), Colour(0.7, 0.3, 0.6));
 	rt.addlight(&light1);