diff --git a/dom/xml/nsXMLContentSink.cpp b/dom/xml/nsXMLContentSink.cpp
index 263008e0701..a8870e43f94 100644
--- a/dom/xml/nsXMLContentSink.cpp
+++ b/dom/xml/nsXMLContentSink.cpp
@@ -518,7 +518,7 @@ nsresult nsXMLContentSink::CreateElement(
       HasCustomElementRegistryAttr(aAtts);
 
   // Step 7: Look up a custom element definition.
-  CustomElementDefinition* customElementDefinition = nullptr;
+  RefPtr<CustomElementDefinition> customElementDefinition;
   nsAtom* nameAtom = ni->NameAtom();
   if (!hasCustomElementRegistryAttr && mDocument &&
       !mDocument->IsLoadedAsData() && isXHTMLOrXUL &&
diff --git a/parser/html/nsHtml5TreeOperation.cpp b/parser/html/nsHtml5TreeOperation.cpp
index c0470efb683..2ad605a58e3 100644
--- a/parser/html/nsHtml5TreeOperation.cpp
+++ b/parser/html/nsHtml5TreeOperation.cpp
@@ -716,7 +716,7 @@ nsIContent* nsHtml5TreeOperation::CreateHTMLElement(
   // 7. Let definition be the result of looking up a custom element definition
   // given registry, namespace, localName, and is.
   const bool isCustomElement = aCreator == NS_NewCustomElement || isAtom;
-  CustomElementDefinition* customElementDefinition = nullptr;
+  RefPtr<CustomElementDefinition> customElementDefinition;
 
   /// customElementDefinition is only used if willExecuteScript is true,
   /// which will only be the case if parser is not in fragment parsing.