diff --git a/intern/cycles/render/osl.cpp b/intern/cycles/render/osl.cpp
index 04af9b48280..8bf32fdcb1a 100644
--- a/intern/cycles/render/osl.cpp
+++ b/intern/cycles/render/osl.cpp
@@ -102,7 +102,7 @@ void OSLShaderManager::device_update(Device *device, DeviceScene *dscene, Scene
 	/* setup shader engine */
 	og->ss = ss;
 	int background_id = scene->shader_manager->get_shader_id(scene->default_background);
-	og->background_state = og->surface_state[background_id];
+	og->background_state = og->surface_state[background_id & SHADER_MASK];
 	og->use = true;
 
 	tls_create(OSLGlobals::ThreadData, og->thread_data);