diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow_PX4Flow.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow_PX4Flow.cpp
index 1773d21a28..115be975a8 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow_PX4Flow.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow_PX4Flow.cpp
@@ -66,7 +66,7 @@ bool AP_OpticalFlow_PX4Flow::scan_buses(void)
         if (!tdev) {
             continue;
         }
-        if (!tdev->get_semaphore()->take(0)) {
+        if (!tdev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
             continue;
         }
         struct i2c_integral_frame frame;
diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow_Pixart.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow_Pixart.cpp
index 6d9e14284a..50e27dd196 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow_Pixart.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow_Pixart.cpp
@@ -100,7 +100,7 @@ AP_OpticalFlow_Pixart *AP_OpticalFlow_Pixart::detect(OpticalFlow &_frontend)
 // setup the device
 bool AP_OpticalFlow_Pixart::setup_sensor(void)
 {
-    if (!_dev->get_semaphore()->take(0)) {
+    if (!_dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         AP_HAL::panic("Unable to get bus semaphore");
     }
 
@@ -278,7 +278,7 @@ void AP_OpticalFlow_Pixart::timer(void)
     float dt = dt_us * 1.0e-6;
     const Vector3f &gyro = get_ahrs().get_gyro();
 
-    if (_sem->take(0)) {
+    if (_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         integral.sum.x += burst.delta_x;
         integral.sum.y += burst.delta_y;
         integral.sum_us += dt_us;
@@ -316,7 +316,7 @@ void AP_OpticalFlow_Pixart::update(void)
     state.device_id = 1;
     state.surface_quality = burst.squal;
     
-    if (integral.sum_us > 0 && _sem->take(0)) {
+    if (integral.sum_us > 0 && _sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         const Vector2f flowScaler = _flowScaler();
         float flowScaleFactorX = 1.0f + 0.001f * flowScaler.x;
         float flowScaleFactorY = 1.0f + 0.001f * flowScaler.y;
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_LightWareI2C.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_LightWareI2C.cpp
index df614d8e42..65f5c06ff9 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_LightWareI2C.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_LightWareI2C.cpp
@@ -45,7 +45,7 @@ AP_RangeFinder_Backend *AP_RangeFinder_LightWareI2C::detect(RangeFinder &_ranger
         return nullptr;
     }
 
-    if (sensor->_dev->get_semaphore()->take(0)) {
+    if (sensor->_dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         uint16_t reading_cm;
         if (!sensor->get_reading(reading_cm)) {
             sensor->_dev->get_semaphore()->give();
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarI2CXL.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarI2CXL.cpp
index aa71da045c..931300f98a 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarI2CXL.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarI2CXL.cpp
@@ -68,7 +68,7 @@ AP_RangeFinder_Backend *AP_RangeFinder_MaxsonarI2CXL::detect(RangeFinder &_range
  */
 bool AP_RangeFinder_MaxsonarI2CXL::_init(void)
 {
-    if (!_dev->get_semaphore()->take(0)) {
+    if (!_dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         return false;
     }
     
@@ -130,7 +130,7 @@ void AP_RangeFinder_MaxsonarI2CXL::_timer(void)
 {
     uint16_t d;
     if (get_reading(d)) {
-        if (_sem->take(0)) {
+        if (_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
             distance = d;
             new_distance = true;
             _sem->give();
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
index e5bb46fb42..98cd9fc1ed 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_PulsedLightLRF.cpp
@@ -142,7 +142,7 @@ static const struct settings_table settings_v2[] = {
  */
 bool AP_RangeFinder_PulsedLightLRF::init(void)
 {
-    if (!_dev || !_dev->get_semaphore()->take(0)) {
+    if (!_dev || !_dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         return false;
     }
     _dev->set_retries(3);
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_trone.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_trone.cpp
index 3d583b5b10..e6a0758bd6 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_trone.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_trone.cpp
@@ -67,7 +67,7 @@ AP_RangeFinder_Backend *AP_RangeFinder_trone::detect(uint8_t bus, RangeFinder &_
  */
 bool AP_RangeFinder_trone::init(void)
 {
-    if (!dev->get_semaphore()->take(0)) {
+    if (!dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         return false;
     }
 
@@ -138,7 +138,7 @@ void AP_RangeFinder_trone::timer(void)
 {
     // take a reading
     uint16_t distance_cm;
-    if (collect(distance_cm) && _sem->take(0)) {
+    if (collect(distance_cm) && _sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         accum.sum += distance_cm;
         accum.count++;
         _sem->give();
@@ -154,7 +154,7 @@ void AP_RangeFinder_trone::timer(void)
 */
 void AP_RangeFinder_trone::update(void)
 {
-    if (_sem->take(0)) {
+    if (_sem->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
         if (accum.count > 0) {
             state.distance_cm = accum.sum / accum.count;
             accum.sum = 0;