diff --git a/gtk2_ardour/pianoroll.cc b/gtk2_ardour/pianoroll.cc
index 72857898f6..bbb77b2615 100644
--- a/gtk2_ardour/pianoroll.cc
+++ b/gtk2_ardour/pianoroll.cc
@@ -2962,6 +2962,13 @@ Pianoroll::select_all_within (Temporal::timepos_t const & start, Temporal::timep
 	commit_reversible_selection_op ();
 }
 
+void
+Pianoroll::session_going_away ()
+{
+	unset (true);
+	CueEditor::session_going_away ();
+}
+
 void
 Pianoroll::set_session (ARDOUR::Session* s)
 {
diff --git a/gtk2_ardour/pianoroll.h b/gtk2_ardour/pianoroll.h
index 7e3ea2c0b7..3df5c5ad3d 100644
--- a/gtk2_ardour/pianoroll.h
+++ b/gtk2_ardour/pianoroll.h
@@ -142,6 +142,7 @@ class Pianoroll : public CueEditor
 
 	PianorollMidiView* midi_view() const { return view; }
 	void set_session (ARDOUR::Session*);
+	void session_going_away ();
 	bool allow_trim_cursors () const;
 
 	void shift_midi (Temporal::timepos_t const &, bool model);