diff --git a/AntennaTracker/Tracker.h b/AntennaTracker/Tracker.h
index 8066fe18de..937cccebcb 100644
--- a/AntennaTracker/Tracker.h
+++ b/AntennaTracker/Tracker.h
@@ -114,7 +114,7 @@ private:
 
     AP_InertialSensor ins;
 
-    RangeFinder rng;
+    RangeFinder rng {serial_manager};
 
 // Inertial Navigation EKF
 #if AP_AHRS_NAVEKF_AVAILABLE