diff --git a/layout/xul/tree/nsTreeBodyFrame.cpp b/layout/xul/tree/nsTreeBodyFrame.cpp
index c8a1d5d78..8b74375cd 100644
--- a/layout/xul/tree/nsTreeBodyFrame.cpp
+++ b/layout/xul/tree/nsTreeBodyFrame.cpp
@@ -589,6 +589,8 @@ nsTreeBodyFrame::GetSelectionRegion(nsIScriptableRegion **aRegion)
 {
   *aRegion = nullptr;
 
+  if (!mView) return NS_OK;
+
   nsCOMPtr<nsITreeSelection> selection;
   mView->GetSelection(getter_AddRefs(selection));
   NS_ENSURE_TRUE(selection, NS_OK);
diff --git a/parser/html/nsHtml5OwningUTF16Buffer.h b/parser/html/nsHtml5OwningUTF16Buffer.h
index d7e3200ea..0d8777464 100644
--- a/parser/html/nsHtml5OwningUTF16Buffer.h
+++ b/parser/html/nsHtml5OwningUTF16Buffer.h
@@ -52,7 +52,7 @@ public:
     nsrefcnt AddRef();
     nsrefcnt Release();
   private:
-    nsAutoRefCnt mRefCnt;
+    mozilla::ThreadSafeAutoRefCnt mRefCnt;
 };
 
 #endif // nsHtml5OwningUTF16Buffer_h