diff --git a/y2020/vision/viewer.cc b/y2020/vision/viewer.cc
index d923407..ff08f01 100644
--- a/y2020/vision/viewer.cc
+++ b/y2020/vision/viewer.cc
@@ -1,9 +1,10 @@
 #include <map>
+#include <random>
+
 #include <opencv2/calib3d.hpp>
 #include <opencv2/features2d.hpp>
 #include <opencv2/highgui/highgui.hpp>
 #include <opencv2/imgproc.hpp>
-#include <random>
 
 #include "aos/events/shm_event_loop.h"
 #include "aos/init.h"