diff --git a/extensions/xforms/nsXFormsModelElement.cpp b/extensions/xforms/nsXFormsModelElement.cpp
index b9506acd9e76..53d2e38dfe6f 100644
--- a/extensions/xforms/nsXFormsModelElement.cpp
+++ b/extensions/xforms/nsXFormsModelElement.cpp
@@ -408,7 +408,8 @@ nsXFormsModelElement::InitializeInstances()
     // Parse the whitespace-separated list.
     nsCOMPtr<nsIContent> content = do_QueryInterface(mElement);
     nsRefPtr<nsIURI> baseURI = content->GetBaseURI();
-    nsRefPtr<nsIURI> docURI = content->GetDocumentURI();
+    nsRefPtr<nsIURI> docURI = content->GetOwnerDoc() ?
+      content->GetOwnerDoc()->GetDocumentURI() : nsnull;
 
     nsCStringArray schemas;
     schemas.ParseString(NS_ConvertUTF16toUTF8(schemaList).get(), " \t\r\n");