diff --git a/testing/web-platform/tests/mathml/relations/css-styling/not-participating-to-parent-layout.html b/testing/web-platform/tests/mathml/relations/css-styling/not-participating-to-parent-layout.html
index 1d7cb0124524..af376a3d5ebe 100644
--- a/testing/web-platform/tests/mathml/relations/css-styling/not-participating-to-parent-layout.html
+++ b/testing/web-platform/tests/mathml/relations/css-styling/not-participating-to-parent-layout.html
@@ -418,6 +418,80 @@
 elementContainer
 )
 ;
+if
+(
+style
+=
+=
+=
+"
+display
+:
+contents
+"
+&
+&
+!
+element
+.
+classList
+.
+contains
+(
+"
+mathml
+-
+container
+"
+)
+)
+{
+/
+/
+A
+"
+display
+:
+contents
+"
+MathML
+child
+is
+not
+participating
+to
+/
+/
+parent
+layout
+because
+its
+computed
+style
+is
+"
+display
+:
+none
+"
+.
+/
+/
+If
+we
+cannot
+append
+a
+MathML
+child
+then
+skip
+that
+test
+.
+return
+;
+}
 FragmentHelper
 .
 forceNonEmptyElement