diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_BLPing.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_BLPing.cpp
index 3cd40aa298..e7776e0f95 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_BLPing.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_BLPing.cpp
@@ -61,10 +61,9 @@ bool AP_RangeFinder_BLPing::get_reading(float &reading_m)
     } averageStruct;
 
     // read any available lines from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        const int16_t b = uart->read();
-        if (b < 0) {
+    for (auto i=0; i<8192; i++) {
+        uint8_t b;
+        if (!uart->read(b)) {
             break;
         }
         if (protocol.parse_byte(b) == PingProtocol::MessageId::DISTANCE_SIMPLE) {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_Benewake.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_Benewake.cpp
index ceea2fd168..f04056588d 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_Benewake.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_Benewake.cpp
@@ -59,13 +59,11 @@ bool AP_RangeFinder_Benewake::get_reading(float &reading_m)
     uint16_t count_out_of_range = 0;
 
     // read any available lines from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        int16_t r = uart->read();
-        if (r < 0) {
-            continue;
+    for (auto j=0; j<8192; j++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
         }
-        uint8_t c = (uint8_t)r;
         // if buffer is empty and this byte is 0x59, add to buffer
         if (linebuf_len == 0) {
             if (c == BENEWAKE_FRAME_HEADER) {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_Lanbao.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_Lanbao.cpp
index d59b030e50..16c37db38f 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_Lanbao.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_Lanbao.cpp
@@ -46,10 +46,9 @@ bool AP_RangeFinder_Lanbao::get_reading(float &reading_m)
     // format is: [ 0xA5 | 0x5A | distance-MSB-mm | distance-LSB-mm | crc16 ]
 
     // read any available lines from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        int16_t b = uart->read();
-        if (b == -1) {
+    for (auto i=0; i<8192; i++) {
+        uint8_t b;
+        if (!uart->read(b)) {
             break;
         }
         if (buf_len == 0 && b != 0xA5) {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_LeddarVu8.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_LeddarVu8.cpp
index 04e38624e0..3d90877d83 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_LeddarVu8.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_LeddarVu8.cpp
@@ -51,13 +51,12 @@ bool AP_RangeFinder_LeddarVu8::get_reading(float &reading_m)
     bool latest_dist_valid = false;
 
     // read any available characters from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        int16_t r = uart->read();
-        if (r < 0) {
-            continue;
+    for (auto i=0; i<8192; i++) {
+        uint8_t b;
+        if (!uart->read(b)) {
+            break;
         }
-        if (parse_byte((uint8_t)r, latest_dist_valid, latest_dist_cm)) {
+        if (parse_byte(b, latest_dist_valid, latest_dist_cm)) {
             if (latest_dist_valid) {
                 sum_cm += latest_dist_cm;
                 count++;
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_LightWareSerial.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_LightWareSerial.cpp
index 9636b47bf2..61c2ed9c2d 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_LightWareSerial.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_LightWareSerial.cpp
@@ -40,10 +40,11 @@ bool AP_RangeFinder_LightWareSerial::get_reading(float &reading_m)
     const int16_t distance_cm_max = max_distance_cm();
 
     // read any available lines from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        char c = uart->read();
-
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         // use legacy protocol
         if (protocol_state == ProtocolState::UNKNOWN || protocol_state == ProtocolState::LEGACY) {
             if (c == '\r') {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp
index 7f0173947c..50abcc6bce 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp
@@ -42,11 +42,13 @@ bool AP_RangeFinder_MaxsonarSerialLV::get_reading(float &reading_m)
     }
 
     int32_t sum = 0;
-    int16_t nbytes = uart->available();
     uint16_t count = 0;
 
-    while (nbytes-- > 0) {
-        char c = uart->read();
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         if (c == '\r') {
             linebuf[linebuf_len] = 0;
             sum += (int)atoi(linebuf);
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_NMEA.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_NMEA.cpp
index 61945ca7c3..bc6a3cf391 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_NMEA.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_NMEA.cpp
@@ -32,9 +32,11 @@ bool AP_RangeFinder_NMEA::get_reading(float &reading_m)
     // read any available lines from the lidar
     float sum = 0.0f;
     uint16_t count = 0;
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        char c = uart->read();
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         if (decode(c)) {
             sum += _distance_m;
             count++;
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_TeraRanger_Serial.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_TeraRanger_Serial.cpp
index e9a502de79..088472b6b8 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_TeraRanger_Serial.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_TeraRanger_Serial.cpp
@@ -54,13 +54,11 @@ bool AP_RangeFinder_TeraRanger_Serial::get_reading(float &reading_m)
     uint16_t bad_read = 0;
 
     // read any available lines from the lidar
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        int16_t r = uart->read();
-        if (r < 0) {
-            continue;
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
         }
-        uint8_t c = (uint8_t)r;
         // if buffer is empty and this byte is 0x57, add to buffer
         if (linebuf_len == 0) {
             if (c == FRAME_HEADER) {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_USD1_Serial.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_USD1_Serial.cpp
index 04d8c06329..26328657d1 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_USD1_Serial.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_USD1_Serial.cpp
@@ -39,11 +39,11 @@ bool AP_RangeFinder_USD1_Serial::detect_version(void)
     uint8_t count = 0;
 
     // read any available data from USD1_Serial
-    int16_t nbytes = uart->available();
-
-    while (nbytes-- > 0) {
-        uint8_t c = uart->read();
-        
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         if (((c == USD1_HDR_V0) || (c == USD1_HDR)) && !hdr_found) {
             byte1 = c;
             hdr_found = true;
@@ -121,11 +121,11 @@ bool AP_RangeFinder_USD1_Serial::get_reading(float &reading_m)
     uint16_t count = 0;
     bool hdr_found = false;
 
-    int16_t nbytes = uart->available();
-
-    while (nbytes-- > 0) {
-        uint8_t c = uart->read();
-        
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         if ((c == _header) && !hdr_found) {
             // located header byte
             _linebuf_len = 0;
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_Wasp.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_Wasp.cpp
index cda423c79b..5885b2af14 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_Wasp.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_Wasp.cpp
@@ -86,9 +86,11 @@ bool AP_RangeFinder_Wasp::get_reading(float &reading_m) {
     // read any available lines from the lidar
     float sum = 0;
     uint16_t count = 0;
-    int16_t nbytes = uart->available();
-    while (nbytes-- > 0) {
-        char c = uart->read();
+    for (auto i=0; i<8192; i++) {
+        uint8_t c;
+        if (!uart->read(c)) {
+            break;
+        }
         if (c == '\n') {
             linebuf[linebuf_len] = 0;
             linebuf_len = 0;