diff --git a/Tools/Replay/Replay.h b/Tools/Replay/Replay.h
index 2e72bb5ba5..fd1c4b2a77 100644
--- a/Tools/Replay/Replay.h
+++ b/Tools/Replay/Replay.h
@@ -31,7 +31,7 @@ class ReplayVehicle : public AP_Vehicle {
 public:
     friend class Replay;
 
-    ReplayVehicle() { unused = -1; }
+    ReplayVehicle() { unused.set(-1); }
     // HAL::Callbacks implementation.
     void load_parameters(void) override;
     void get_scheduler_tasks(const AP_Scheduler::Task *&tasks,