diff --git a/shadow-dom/declarative/declarative-shadow-dom-basic.html b/shadow-dom/declarative/declarative-shadow-dom-basic.html
index 5d59c9bb2f70c3..6f3739b63ca43a 100644
--- a/shadow-dom/declarative/declarative-shadow-dom-basic.html
+++ b/shadow-dom/declarative/declarative-shadow-dom-basic.html
@@ -39,9 +39,9 @@
   t.setAttribute('shadowrootmode','OpEn');
   assert_equals(t.shadowRootMode,'open','Case insensitive');
   t.setAttribute('shadowrootmode','INVALID');
-  assert_equals(t.shadowRootMode,null,'Invalid values map to null');
+  assert_equals(t.shadowRootMode,'','Invalid values map to empty string');
   t.removeAttribute('shadowrootmode');
-  assert_equals(t.shadowRootMode,null,'No shadowrootmode attribute maps to null');
+  assert_equals(t.shadowRootMode,'','No shadowrootmode attribute maps to empty string');
 }, 'Shadowrootmode reflection');
 
 test(() => {