diff --git a/libs/ardour/ardour/source.h b/libs/ardour/ardour/source.h
index d484709ef6..4687f0b55c 100644
--- a/libs/ardour/ardour/source.h
+++ b/libs/ardour/ardour/source.h
@@ -113,10 +113,10 @@ public:
 	void set_captured_xruns (XrunPositions const& xruns) { _xruns = xruns; }
 
 	CueMarkers const & cue_markers() const { return _cue_markers; }
-	void add_cue_marker (CueMarker const &);
-	void move_cue_marker (CueMarker const &, samplepos_t source_relative_position);
+	bool add_cue_marker (CueMarker const &);
+	bool move_cue_marker (CueMarker const &, samplepos_t source_relative_position);
 	bool remove_cue_marker (CueMarker const &);
-	void rename_cue_marker (CueMarker&, std::string const &);
+	bool rename_cue_marker (CueMarker&, std::string const &);
 	bool clear_cue_markers ();
 	PBD::Signal0<void> CueMarkersChanged;
 
diff --git a/libs/ardour/source.cc b/libs/ardour/source.cc
index f4518a379f..ce52c20a14 100644
--- a/libs/ardour/source.cc
+++ b/libs/ardour/source.cc
@@ -215,6 +215,8 @@ Source::set_state (const XMLNode& node, int version)
 
 		} else if ((*niter)->name() == X_("Cues")) {
 
+			CueMarkers old (_cue_markers);
+
 			_cue_markers.clear ();
 
 			const XMLNode& cues (*(*niter));
@@ -230,6 +232,9 @@ Source::set_state (const XMLNode& node, int version)
 
 				_cue_markers.insert (CueMarker (text, position));
 			}
+
+			cues_changed = (old == _cue_markers);
+			cerr << "reset state, cues changed " << cues_changed << endl;
 		}
 	}
 
@@ -257,6 +262,16 @@ Source::set_state (const XMLNode& node, int version)
 		_flags = Flag (_flags & ~(Writable|Removable|RemovableIfEmpty|RemoveAtDestroy|CanRename));
 	}
 
+	/* support to make undo/redo actually function. Very few things about
+	 * Sources are ever part of undo/redo history, but this can
+	 * be. Undo/Redo uses a MementoCommand<> pattern, which will not in
+	 * itself notify anyone when the operation changes the cue markers.
+	 */
+
+	if (cues_changed) {
+		CueMarkersChanged (); /* EMIT SIGNAL */
+	}
+
 	return 0;
 }
 
@@ -413,34 +428,42 @@ Source::writable () const
         return (_flags & Writable) && _session.writable();
 }
 
-void
+bool
 Source::add_cue_marker (CueMarker const & cm)
 {
-	_cue_markers.insert (cm);
-	CueMarkersChanged(); /* EMIT SIGNAL */
+	if (_cue_markers.insert (cm).second) {
+		CueMarkersChanged(); /* EMIT SIGNAL */
+		return true;
+	}
+
+	return false;
 }
 
-void
+bool
 Source::move_cue_marker (CueMarker const & cm, samplepos_t source_relative_position)
 {
 	if (source_relative_position > length (0)) {
-		return;
+		return false;
 	}
 
 	if (remove_cue_marker (cm)) {
-		add_cue_marker (CueMarker (cm.text(), source_relative_position));
+		return add_cue_marker (CueMarker (cm.text(), source_relative_position));
 	}
+
+	return false;
 }
 
-void
+bool
 Source::rename_cue_marker (CueMarker& cm, std::string const & str)
 {
 	CueMarkers::iterator m = _cue_markers.find (cm);
 
 	if (m != _cue_markers.end()) {
 		_cue_markers.erase (m);
-		add_cue_marker (CueMarker (str, cm.position()));
+		return add_cue_marker (CueMarker (str, cm.position()));
 	}
+
+	return false;
 }
 
 bool