1 files changed, 5 insertions, 2 deletions
diff --git a/parser/html/nsHtml5TreeOperation.cpp b/parser/html/nsHtml5TreeOperation.cpp
index a7d3da2595..d530cbba3a 100644
--- a/parser/html/nsHtml5TreeOperation.cpp
+++ b/parser/html/nsHtml5TreeOperation.cpp
@@ -429,9 +429,12 @@ nsHtml5TreeOperation::CreateHTMLElement(
 
     isCustomElement = (aCreator == NS_NewCustomElement || !isValue.IsEmpty());
     if (isCustomElement && aFromParser != dom::FROM_PARSER_FRAGMENT) {
+      RefPtr<nsIAtom> tagAtom = nodeInfo->NameAtom();
+      RefPtr<nsIAtom> typeAtom =
+        isValue.IsEmpty() ? tagAtom : NS_Atomize(isValue);
+
       definition = nsContentUtils::LookupCustomElementDefinition(document,
-        nodeInfo->LocalName(), nodeInfo->NamespaceID(),
-        (isValue.IsEmpty() ? nullptr : &isValue));
+        nodeInfo->LocalName(), nodeInfo->NamespaceID(), typeAtom);
 
       if (definition) {
         willExecuteScript = true;