diff --git a/src/session_base.hpp b/src/session_base.hpp
index c2e6d098..e96e0533 100644
--- a/src/session_base.hpp
+++ b/src/session_base.hpp
@@ -113,7 +113,7 @@ class session_base_t : public own_t, public io_object_t, public i_pipe_events
     void process_plug () ZMQ_FINAL;
     void process_attach (zmq::i_engine *engine_) ZMQ_FINAL;
     void process_term (int linger_) ZMQ_FINAL;
-    void process_conn_failed ();
+    void process_conn_failed () ZMQ_OVERRIDE;
 
     //  i_poll_events handlers.
     void timer_event (int id_) ZMQ_FINAL;
diff --git a/src/stream_engine_base.hpp b/src/stream_engine_base.hpp
index 58bf9579..05bcc659 100644
--- a/src/stream_engine_base.hpp
+++ b/src/stream_engine_base.hpp
@@ -73,7 +73,7 @@ class stream_engine_base_t : public io_object_t, public i_engine
 
     //  i_poll_events interface implementation.
     void in_event () ZMQ_FINAL;
-    void out_event ();
+    void out_event () ZMQ_OVERRIDE;
     void timer_event (int id_) ZMQ_FINAL;
 
   protected: