diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
index 5a80550e36..750e4f635d 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
@@ -30,7 +30,7 @@ extern const AP_HAL::HAL& hal;
 AP_RangeFinder_PulsedLightLRF::AP_RangeFinder_PulsedLightLRF(RangeFinder &_ranger, uint8_t instance,
                                                              RangeFinder::RangeFinder_State &_state)
     : AP_RangeFinder_Backend(_ranger, instance, _state)
-    , _dev(hal.i2c_mgr->get_device(0, AP_RANGEFINDER_PULSEDLIGHTLRF_ADDR))
+    , _dev(hal.i2c_mgr->get_device(1, AP_RANGEFINDER_PULSEDLIGHTLRF_ADDR))
 {
 }
 
@@ -44,8 +44,7 @@ AP_RangeFinder_Backend *AP_RangeFinder_PulsedLightLRF::detect(RangeFinder &_rang
 {
     AP_RangeFinder_PulsedLightLRF *sensor
         = new AP_RangeFinder_PulsedLightLRF(_ranger, instance, _state);
-
-    if (!sensor->start_reading()) {
+    if (!sensor || !sensor->start_reading()) {
         delete sensor;
         return nullptr;
     }
@@ -64,7 +63,7 @@ AP_RangeFinder_Backend *AP_RangeFinder_PulsedLightLRF::detect(RangeFinder &_rang
 // start_reading() - ask sensor to make a range reading
 bool AP_RangeFinder_PulsedLightLRF::start_reading()
 {
-    if (!_dev->get_semaphore()->take(1)) {
+    if (!_dev || !_dev->get_semaphore()->take(1)) {
         return false;
     }
 
@@ -72,6 +71,7 @@ bool AP_RangeFinder_PulsedLightLRF::start_reading()
     bool ret = _dev->write_register(AP_RANGEFINDER_PULSEDLIGHTLRF_MEASURE_REG,
                                     AP_RANGEFINDER_PULSEDLIGHTLRF_MSRREG_ACQUIRE);
     _dev->get_semaphore()->give();
+
     return ret;
 }