diff --git a/src/backend/interfaceregistry.c b/src/backend/interfaceregistry.c
index 05e2224a1..180c2043f 100644
--- a/src/backend/interfaceregistry.c
+++ b/src/backend/interfaceregistry.c
@@ -106,7 +106,7 @@ lumiera_interfaceregistry_init (void)
   if (!lumiera_interfaceregistry)
     LUMIERA_DIE (ERRNO);
 
-  lumiera_pluginregistry = psplay_new (lumiera_plugin_cmp_fn, lumiera_plugin_key_fn, NULL);
+  lumiera_pluginregistry = psplay_new (lumiera_plugin_cmp_fn, lumiera_plugin_key_fn, lumiera_plugin_delete_fn);
   if (!lumiera_pluginregistry)
     LUMIERA_DIE (ERRNO);
 
@@ -118,20 +118,18 @@ void
 lumiera_interfaceregistry_destroy (void)
 {
   TRACE (interfaceregistry);
-  REQUIRE (!psplay_nelements (lumiera_interfaceregistry));
-
-  lumiera_mutex_destroy (&lumiera_interface_mutex, &NOBUG_FLAG(interfaceregistry));
-
-  if (lumiera_interfaceregistry)
-    psplay_destroy (lumiera_interfaceregistry);
-  lumiera_interfaceregistry = NULL;
-
-  TODO ("provide a delete function for the psplay tree to tear it down");
-  REQUIRE (psplay_nelements (lumiera_pluginregistry) == 0, "plugins still loaded at destroy");
 
   if (lumiera_pluginregistry)
     psplay_delete (lumiera_pluginregistry);
   lumiera_pluginregistry = NULL;
+
+  lumiera_mutex_destroy (&lumiera_interface_mutex, &NOBUG_FLAG(interfaceregistry));
+
+  REQUIRE (!psplay_nelements (lumiera_interfaceregistry), "some interfaces still registered at shutdown");
+
+  if (lumiera_interfaceregistry)
+    psplay_destroy (lumiera_interfaceregistry);
+  lumiera_interfaceregistry = NULL;
 }
 
 
diff --git a/src/backend/plugin.c b/src/backend/plugin.c
index 69bac0525..23d9aeed1 100644
--- a/src/backend/plugin.c
+++ b/src/backend/plugin.c
@@ -362,3 +362,31 @@ lumiera_plugin_key_fn (const PSplaynode node)
   return ((LumieraPlugin)node)->name;
 }
 
+
+void
+lumiera_plugin_delete_fn (PSplaynode node)
+{
+  LumieraPlugin self = (LumieraPlugin) node;
+
+  ENSURE (!self->refcnt, "plugin %s still in use at shutdown", self->name);
+
+
+  const char* ext = strrchr (self->name, '.');
+
+  LumieraPlugintype itr = lumiera_plugin_types;
+  while (itr->ext)
+    {
+      if (!strcmp (itr->ext, ext))
+        {
+          if (!self->error)
+            {
+              LUMIERA_INTERFACE_HANDLE(lumieraorg__plugin, 0) handle =
+                LUMIERA_INTERFACE_CAST(lumieraorg__plugin, 0) self->plugin;
+              lumiera_interfaceregistry_bulkremove_interfaces (handle->plugin_interfaces ());
+            }
+          itr->lumiera_plugin_unload_fn (self);
+          break;
+        }
+      ++itr;
+    }
+}
diff --git a/src/backend/plugin.h b/src/backend/plugin.h
index dcf9180f1..b7ccd5326 100644
--- a/src/backend/plugin.h
+++ b/src/backend/plugin.h
@@ -174,5 +174,7 @@ lumiera_plugin_cmp_fn (const void* keya, const void* keyb);
 const void*
 lumiera_plugin_key_fn (const PSplaynode node);
 
+void
+lumiera_plugin_delete_fn (PSplaynode node);
 
 #endif /* LUMIERA_PLUGIN_H */
diff --git a/src/backend/plugin_dynlib.c b/src/backend/plugin_dynlib.c
index 75ce4aa89..50030843c 100644
--- a/src/backend/plugin_dynlib.c
+++ b/src/backend/plugin_dynlib.c
@@ -54,5 +54,7 @@ void
 lumiera_plugin_unload_DYNLIB (LumieraPlugin self)
 {
   TRACE (plugin);
-  dlclose (lumiera_plugin_handle (self));
+  void* handle = lumiera_plugin_handle (self);
+  if (handle)
+    dlclose (handle);
 }