diff --git a/ArduSub/Sub.h b/ArduSub/Sub.h
index bbe02d5ec1..fd8962abcd 100644
--- a/ArduSub/Sub.h
+++ b/ArduSub/Sub.h
@@ -178,7 +178,7 @@ private:
     Compass compass;
     AP_InertialSensor ins;
 
-    RangeFinder rangefinder{serial_manager};
+    RangeFinder rangefinder;
     struct {
         bool enabled:1;
         bool alt_healthy:1; // true if we can trust the altitude from the rangefinder