diff --git a/src/scene.cc b/src/scene.cc
index 669c3b6..8905b75 100644
--- a/src/scene.cc
+++ b/src/scene.cc
@@ -19,6 +19,7 @@
 Scene::Scene()
     : width(640), height(480),
       max_depth(5),
+      ambient(NULL),
       nrays(0),
       pixels(NULL)
 { }
diff --git a/src/scene.h b/src/scene.h
index 58031b4..7a01f18 100644
--- a/src/scene.h
+++ b/src/scene.h
@@ -50,6 +50,7 @@ private:
     int max_depth;
 
     // Scene objects.
+    AmbientLight *ambient;
     std::list<Shape *> shapes;
     std::list<PointLight *> lights;