diff --git a/editor/composer/src/nsEditorSpellCheck.cpp b/editor/composer/src/nsEditorSpellCheck.cpp
index 3778f8f0a31..5eed950c5e4 100644
--- a/editor/composer/src/nsEditorSpellCheck.cpp
+++ b/editor/composer/src/nsEditorSpellCheck.cpp
@@ -83,7 +83,7 @@ class UpdateDictionnaryHolder {
 
 #define CPS_PREF_NAME NS_LITERAL_STRING("spellcheck.lang")
 
-class LastDictionary {
+class LastDictionary MOZ_FINAL {
 public:
   /**
    * Store current dictionary for editor document url. Use content pref
diff --git a/editor/libeditor/html/nsHTMLAnonymousUtils.cpp b/editor/libeditor/html/nsHTMLAnonymousUtils.cpp
index b84725db881..923bfbd2fe9 100644
--- a/editor/libeditor/html/nsHTMLAnonymousUtils.cpp
+++ b/editor/libeditor/html/nsHTMLAnonymousUtils.cpp
@@ -102,7 +102,7 @@ static PRInt32 GetCSSFloatValue(nsIDOMCSSStyleDeclaration * aDecl,
   return (PRInt32) f;
 }
 
-class nsElementDeletionObserver : public nsIMutationObserver
+class nsElementDeletionObserver MOZ_FINAL : public nsIMutationObserver
 {
 public:
   nsElementDeletionObserver(nsINode* aNativeAnonNode, nsINode* aObservedNode)