diff --git a/libs/pbd/controllable.cc b/libs/pbd/controllable.cc
index 5d9b924ab5..16e03d8827 100644
--- a/libs/pbd/controllable.cc
+++ b/libs/pbd/controllable.cc
@@ -100,6 +100,18 @@ Controllable::set_flags (Flag f)
 	_flags = f;
 }
 
+void
+Controllable::set_flag (Flag f)
+{
+	_flags = Flag ((int)_flags | f);
+}
+
+void
+Controllable::clear_flag (Flag f)
+{
+	_flags = Flag ((int)_flags & ~f);
+}
+
 void
 Controllable::add (Controllable& ctl)
 {
diff --git a/libs/pbd/pbd/controllable.h b/libs/pbd/pbd/controllable.h
index 95e75eb3be..05e014caf4 100644
--- a/libs/pbd/pbd/controllable.h
+++ b/libs/pbd/pbd/controllable.h
@@ -163,6 +163,9 @@ public:
 	Flag flags() const { return _flags; }
 	void set_flags (Flag f);
 
+	void set_flag (Flag f); ///< _flags |= f;
+	void clear_flag (Flag f); ///< _flags &= ~f;
+
 	static boost::shared_ptr<Controllable> by_id (const PBD::ID&);
 	static void dump_registry ();