Index: libs/ardour/lv2_plugin_lilv.cc
===================================================================
--- libs/ardour/lv2_plugin_lilv.cc	(revision 10790)
+++ libs/ardour/lv2_plugin_lilv.cc	(working copy)
@@ -581,8 +581,10 @@
 	}
 
 	const std::string abs_path = Glib::build_filename(
-		me->_session.plugins_dir(),
-		me->_insert_id.to_s(),
+		Glib::build_filename(
+			me->_session.plugins_dir(),
+			me->_insert_id.to_s()
+		),
 		path);
 
 	const std::string dirname = Glib::path_get_dirname(abs_path);