diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index 4cd77f8c6e1..787e5cf07b2 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -177,6 +177,16 @@ LightManager::~LightManager()
 {
 }
 
+bool LightManager::has_background_light(Scene *scene)
+{
+	foreach(Light *light, scene->lights) {
+		if(light->type == LIGHT_BACKGROUND) {
+			return true;
+		}
+	}
+	return false;
+}
+
 void LightManager::disable_ineffective_light(Device *device, Scene *scene)
 {
 	/* Make all lights enabled by default, and perform some preliminary checks
diff --git a/intern/cycles/render/light.h b/intern/cycles/render/light.h
index 745caa96159..040a672937d 100644
--- a/intern/cycles/render/light.h
+++ b/intern/cycles/render/light.h
@@ -91,6 +91,9 @@ public:
 
 	void tag_update(Scene *scene);
 
+	/* Check whether there is a background light. */
+	bool has_background_light(Scene *scene);
+
 protected:
 	/* Optimization: disable light which is either unsupported or
 	 * which doesn't contribute to the scene or which is only used for MIS
diff --git a/intern/cycles/render/shader.cpp b/intern/cycles/render/shader.cpp
index 165a316ea76..10c3507e3f4 100644
--- a/intern/cycles/render/shader.cpp
+++ b/intern/cycles/render/shader.cpp
@@ -221,6 +221,16 @@ void Shader::tag_update(Scene *scene)
 	if(use_mis && has_surface_emission)
 		scene->light_manager->need_update = true;
 
+	/* Special handle of background MIS light for now: for some reason it
+	 * has use_mis set to false. We are quite close to release now, so
+	 * better to be safe.
+	 */
+	if(this == scene->default_background &&
+	   scene->light_manager->has_background_light(scene))
+	{
+		scene->light_manager->need_update = true;
+	}
+
 	/* quick detection of which kind of shaders we have to avoid loading
 	 * e.g. surface attributes when there is only a volume shader. this could
 	 * be more fine grained but it's better than nothing */