diff --git a/libs/pbd/base_ui.cc b/libs/pbd/base_ui.cc
index 83df2b76b5..6c9a095d6d 100644
--- a/libs/pbd/base_ui.cc
+++ b/libs/pbd/base_ui.cc
@@ -119,11 +119,12 @@ BaseUI::run ()
 
 	m_context = MainContext::create();
 	_main_loop = MainLoop::create (m_context);
-	attach_request_source ();
 
 	Glib::Threads::Mutex::Lock lm (_run_lock);
 	_run_loop_thread = PBD::Thread::create (boost::bind (&BaseUI::main_thread, this));
 	_running.wait (_run_lock);
+
+	attach_request_source ();
 }
 
 void