diff --git a/components/layout/query.rs b/components/layout/query.rs
index 4068c3230bf..e25d76b3b46 100644
--- a/components/layout/query.rs
+++ b/components/layout/query.rs
@@ -807,6 +807,8 @@ pub fn process_offset_parent_query<N: LayoutNode>(requested_node: N, layout_root
         -> OffsetParentResponse {
     let mut iterator = ParentOffsetBorderBoxIterator::new(requested_node.opaque());
     sequential::iterate_through_flow_tree_fragment_border_boxes(layout_root, &mut iterator);
+    assert!(iterator.has_found_node);
+
     let parent_info_index = iterator.parent_nodes.iter().rposition(|info| info.is_some());
     match parent_info_index {
         Some(parent_info_index) => {