diff --git a/src/zm_rtsp_server_fifo_video_source.h b/src/zm_rtsp_server_fifo_video_source.h
index b06dbe5a7..765b79092 100644
--- a/src/zm_rtsp_server_fifo_video_source.h
+++ b/src/zm_rtsp_server_fifo_video_source.h
@@ -28,7 +28,7 @@ class ZoneMinderFifoVideoSource: public ZoneMinderFifoSource {
         std::string fifo
         );
   protected:
-    void PushFrame(const uint8_t *data, size_t size, int64_t pts);
+    void PushFrame(const uint8_t *data, size_t size, int64_t pts) override;
 
 	protected:
     int m_width;