diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index e97ced9202aa..015f721fc541 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -3681,6 +3681,7 @@ FlushLayoutRecursive(nsIDocument* aDocument,
                      void* aData = nullptr)
 {
   MOZ_ASSERT(!aData);
+  nsCOMPtr<nsIDocument> kungFuDeathGrip(aDocument);
   aDocument->EnumerateSubDocuments(FlushLayoutRecursive, nullptr);
   aDocument->FlushPendingNotifications(Flush_Layout);
   return true;