diff --git a/libtascar/include/scene.h b/libtascar/include/scene.h
index 7f5f7860..e551dc95 100644
--- a/libtascar/include/scene.h
+++ b/libtascar/include/scene.h
@@ -267,6 +267,7 @@ namespace TASCAR {
 
     private:
       TASCAR::Acousticmodel::diffuse_t* source;
+    public:
       plugin_processor_t plugins;
     };
 
@@ -425,6 +426,7 @@ namespace TASCAR {
     private:
       uint32_t outputlayers;
       TASCAR::Acousticmodel::diffuse_t* source;
+    public:
       plugin_processor_t plugins;
     };
 
diff --git a/libtascar/src/acousticmodel.cc b/libtascar/src/acousticmodel.cc
index 396d0eac..ca206a25 100644
--- a/libtascar/src/acousticmodel.cc
+++ b/libtascar/src/acousticmodel.cc
@@ -38,7 +38,7 @@ float mask_t::gain(const pos_t& p)
 }
 
 diffuse_t::diffuse_t(tsccfg::node_t cfg, uint32_t chunksize,
-                     TASCAR::levelmeter_t& rmslevel_, const std::string& name,
+                     TASCAR::levelmeter_t& rmslevel_, const std::string& ,
                      plugin_processor_t& plugins_)
     : xml_element_t(cfg), licensed_component_t(typeid(*this).name()),
       audio(chunksize), falloff(1.0), active(true), layers(0xffffffff),
diff --git a/libtascar/src/osc_scene.cc b/libtascar/src/osc_scene.cc
index 5e6094a0..bb221a20 100644
--- a/libtascar/src/osc_scene.cc
+++ b/libtascar/src/osc_scene.cc
@@ -324,10 +324,7 @@ void osc_scene_t::add_diffuse_methods(TASCAR::osc_server_t* srv,
   srv->add_method("/lingain", "f", osc_set_diffuse_gain_lin, s);
   srv->add_float_dbspl("/caliblevel", &(s->caliblevel));
   srv->add_uint("/layers", &(s->layers));
-  if(s->get_source())
-    s->get_source()->plugins.add_variables(srv);
-  else
-    throw TASCAR::ErrMsg("implementation error");
+  s->plugins.add_variables(srv);
   srv->set_prefix(oldpref);
 }