diff --git a/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.cpp b/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.cpp
index d246214a1b..881dfb97fd 100644
--- a/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.cpp
+++ b/libraries/AP_OpticalFlow/examples/AP_OpticalFlow_test/AP_OpticalFlow_test.cpp
@@ -26,7 +26,7 @@ public:
     Compass compass;
     AP_InertialSensor ins;
     AP_SerialManager serial_manager;
-    RangeFinder sonar{serial_manager};
+    RangeFinder sonar;
     AP_AHRS_NavEKF ahrs{EKF2, EKF3, AP_AHRS_NavEKF::FLAG_ALWAYS_USE_EKF};
     NavEKF2 EKF2{&ahrs, sonar};
     NavEKF3 EKF3{&ahrs, sonar};