diff --git a/libs/canvas/item.cc b/libs/canvas/item.cc
index 418382da17..e4e3c30546 100644
--- a/libs/canvas/item.cc
+++ b/libs/canvas/item.cc
@@ -404,9 +404,9 @@ Item::bounding_box () const
 {
 	if (_bounding_box_dirty) {
 		compute_bounding_box ();
+		assert (!_bounding_box_dirty);
 	}
 
-	assert (!_bounding_box_dirty);
 	return _bounding_box;
 }