diff --git a/include/lib/model.h b/include/lib/model.h
index 6103a973..fc642dbe 100644
--- a/include/lib/model.h
+++ b/include/lib/model.h
@@ -35,8 +35,8 @@ public:
 	void on_row_deleted(unsigned int);
 	void on_row_changed(unsigned int);
 	void on_path_selected(const Gtk::TreePath &);
-	unsigned int iter_to_id(const Gtk::TreeIter &);
-	unsigned int path_to_id(const Gtk::TreePath &);
+	unsigned int iter_to_id(const Gtk::TreeIter &) const;
+	unsigned int path_to_id(const Gtk::TreePath &) const;
 };
 
 #endif /* OCARINA_LIB_MODEL_H */
diff --git a/lib/model.cpp b/lib/model.cpp
index 0a57aaa8..49afbe1b 100644
--- a/lib/model.cpp
+++ b/lib/model.cpp
@@ -61,12 +61,12 @@ void QueueModel::on_path_selected(const Gtk::TreePath &path)
 	audio :: play();
 }
 
-unsigned int QueueModel :: iter_to_id(const Gtk::TreeIter &iter)
+unsigned int QueueModel :: iter_to_id(const Gtk::TreeIter &iter) const
 {
 	return GPOINTER_TO_UINT(iter.gobj()->user_data);
 }
 
-unsigned int QueueModel::path_to_id(const Gtk::TreePath &path)
+unsigned int QueueModel::path_to_id(const Gtk::TreePath &path) const
 {
 	return queue->operator[](path[0])->index();
 }
@@ -167,7 +167,6 @@ void QueueModel::get_value_str(Track *track, int column,
 void QueueModel::get_value_vfunc(const Gtk::TreeIter &iter, int column,
 				     Glib::ValueBase &value) const
 {
-	unsigned int row;
 	Track *track;
 
 	if (!check_iter_validity(iter))
@@ -176,8 +175,7 @@ void QueueModel::get_value_vfunc(const Gtk::TreeIter &iter, int column,
 	if (column > get_n_columns_vfunc())
 		return;
 
-	row = GPOINTER_TO_UINT(iter.gobj()->user_data);
-	track = queue->operator[](row);
+	track = queue->operator[](iter_to_id(iter));
 
 	switch (column) {
 	case 0:
@@ -193,15 +191,11 @@ void QueueModel::get_value_vfunc(const Gtk::TreeIter &iter, int column,
 bool QueueModel::iter_next_vfunc(const Gtk::TreeIter &iter,
 				     Gtk::TreeIter &iter_next) const
 {
-	unsigned int index;
-
 	if (!check_iter_validity(iter)) {
 		iter_next = Gtk::TreeIter();
 		return false;
 	}
-
-	index = GPOINTER_TO_UINT(iter.gobj()->user_data);
-	return iter_nth_root_child_vfunc(++index, iter_next);
+	return iter_nth_root_child_vfunc(iter_to_id(iter) + 1, iter_next);
 }
 
 int QueueModel::iter_n_root_children_vfunc() const
@@ -225,7 +219,7 @@ Gtk::TreeModel::Path QueueModel::get_path_vfunc(const Gtk::TreeIter &iter) const
 	Gtk::TreeModel::Path path;
 
 	if (check_iter_validity(iter))
-		path.push_back(GPOINTER_TO_UINT(iter.gobj()->user_data));
+		path.push_back(iter_to_id(iter));
 	return path;
 }