diff --git a/gtk2_ardour/editor_canvas_events.cc b/gtk2_ardour/editor_canvas_events.cc
index be2b5c3de7..2f4fe40bcd 100644
--- a/gtk2_ardour/editor_canvas_events.cc
+++ b/gtk2_ardour/editor_canvas_events.cc
@@ -163,7 +163,7 @@ bool
 Editor::canvas_scroll_event (GdkEventScroll *event, bool from_canvas)
 {
 	if (from_canvas) {
-		boost::optional<Rect> rulers = _time_markers_group->bounding_box();
+		boost::optional<ArdourCanvas::Rect> rulers = _time_markers_group->bounding_box();
 		if (rulers && rulers->contains (Duple (event->x, event->y))) {
 			return canvas_ruler_event ((GdkEvent*) event, timecode_ruler, TimecodeRulerItem);
 		}