diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 427c9ed9401..3a38c851bcf 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -162,6 +162,9 @@ pub(crate) struct HTMLImageElement {
form_owner: MutNullableDom,
generation: Cell,
source_set: DomRefCell,
+ ///
+ /// Always non-null after construction.
+ dimension_attribute_source: MutNullableDom,
last_selected_source: DomRefCell