diff --git a/libs/ardour/session_process.cc b/libs/ardour/session_process.cc
index 5891be2..1d12e04 100644
--- a/libs/ardour/session_process.cc
+++ b/libs/ardour/session_process.cc
@@ -55,7 +55,11 @@ Session::process (nframes_t nframes)
 	
 	(this->*process_function) (nframes);
 
-	SendFeedback (); /* EMIT SIGNAL */
+
+	{
+		Glib::Mutex::Lock lm (midi_lock, Glib::TRY_LOCK);
+		SendFeedback (); /* EMIT SIGNAL */
+	}
 }
 
 void