diff --git a/include/IROptimizerObserver.h b/include/IROptimizerObserver.h
index 5c9737b..0498d6b 100644
--- a/include/IROptimizerObserver.h
+++ b/include/IROptimizerObserver.h
@@ -49,10 +49,10 @@ class optimizer_observer_t : public itk::Command
   
   itkNewMacro(Self);
   
-  void Execute(itk::Object *caller, const itk::EventObject & event)
+  void Execute(itk::Object *caller, const itk::EventObject & event) override
   { Execute((const itk::Object *)(caller), event); }
   
-  void Execute(const itk::Object * object, const itk::EventObject & event)
+  void Execute(const itk::Object * object, const itk::EventObject & event) override
   {
     if (typeid(event) != typeid(itk::IterationEvent)) return;