diff --git a/selfdrive/ui/ui.h b/selfdrive/ui/ui.h
index f3229eee99..7ad3b8b562 100644
--- a/selfdrive/ui/ui.h
+++ b/selfdrive/ui/ui.h
@@ -55,7 +55,7 @@ typedef struct Alert {
   QString type;
   cereal::ControlsState::AlertSize size;
   AudibleAlert sound;
-  bool equal(Alert a2) {
+  bool equal(const Alert &a2) {
     return text1 == a2.text1 && text2 == a2.text2 && type == a2.type;
   }
 } Alert;