--- a/dom/xul/XULDocument.cpp
+++ b/dom/xul/XULDocument.cpp
@@ -1111,21 +1111,21 @@ XULDocument::GetElementsByAttribute(cons
     return NS_OK;
 }
 
 already_AddRefed<nsINodeList>
 XULDocument::GetElementsByAttribute(const nsAString& aAttribute,
                                     const nsAString& aValue)
 {
     RefPtr<nsAtom> attrAtom(NS_Atomize(aAttribute));
-    void* attrValue = new nsString(aValue);
+    nsAutoPtr<nsString> attrValue = new nsString(aValue);
     RefPtr<nsContentList> list = new nsContentList(this,
                                             MatchAttribute,
                                             nsContentUtils::DestroyMatchString,
-                                            attrValue,
+                                            reinterpret_cast<void*>(attrValue.forget()),
                                             true,
                                             attrAtom,
                                             kNameSpaceID_Unknown);
 
     return list.forget();
 }
 
 NS_IMETHODIMP