1 files changed, 1 insertions, 1 deletions
diff --git a/components/layout/parallel.rs b/components/layout/parallel.rs
index 628f0c4e07e..e74f9631ff1 100644
--- a/components/layout/parallel.rs
+++ b/components/layout/parallel.rs
@@ -162,7 +162,7 @@ trait ParallelPreorderFlowTraversal : PreorderFlowTraversal {
                 }
 
                 // Possibly enqueue the children.
-                for kid in flow::child_iter(flow) {
+                for kid in flow::child_iter_mut(flow) {
                     had_children = true;
                     discovered_child_flows.push(borrowed_flow_to_unsafe_flow(kid));
                 }