diff --git a/tests/unit/script/size_of.rs b/tests/unit/script/size_of.rs
index 30bc822fdbf7..a328bcbf6f5c 100644
--- a/tests/unit/script/size_of.rs
+++ b/tests/unit/script/size_of.rs
@@ -31,10 +31,10 @@ macro_rules! sizeof_checker (
 // Update the sizes here
 sizeof_checker!(size_event_target, EventTarget, 40);
 sizeof_checker!(size_node, Node, 152);
-sizeof_checker!(size_element, Element, 312);
-sizeof_checker!(size_htmlelement, HTMLElement, 328);
-sizeof_checker!(size_div, HTMLDivElement, 328);
-sizeof_checker!(size_span, HTMLSpanElement, 328);
+sizeof_checker!(size_element, Element, 320);
+sizeof_checker!(size_htmlelement, HTMLElement, 336);
+sizeof_checker!(size_div, HTMLDivElement, 336);
+sizeof_checker!(size_span, HTMLSpanElement, 336);
 sizeof_checker!(size_text, Text, 184);
 sizeof_checker!(size_characterdata, CharacterData, 184);
 sizeof_checker!(size_servothreadsafelayoutnode, ServoThreadSafeLayoutNode, 16);