diff --git a/libraries/GCS_MAVLink/GCS_Common.cpp b/libraries/GCS_MAVLink/GCS_Common.cpp
index 19eb656ab1..5168ca4c26 100644
--- a/libraries/GCS_MAVLink/GCS_Common.cpp
+++ b/libraries/GCS_MAVLink/GCS_Common.cpp
@@ -51,6 +51,12 @@ GCS_MAVLINK::init(AP_HAL::UARTDriver *port, mavlink_channel_t mav_chan)
             mavlink_comm_2_port = _port;
             initialised = true;
             break;
+#endif
+        case MAVLINK_COMM_3:
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+            mavlink_comm_3_port = _port;
+            initialised = true;
+            break;
 #endif
         default:
             // do nothing for unsupport mavlink channels
@@ -441,6 +447,16 @@ bool GCS_MAVLINK::have_flow_control(void)
         break;
 #endif
 
+    case MAVLINK_COMM_3:
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+        if (mavlink_comm_3_port == NULL) {
+            return false;
+        } else {
+            return mavlink_comm_3_port->get_flow_control() != AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE;
+        }
+        break;
+#endif
+
     default:
         break;
     }
diff --git a/libraries/GCS_MAVLink/GCS_MAVLink.cpp b/libraries/GCS_MAVLink/GCS_MAVLink.cpp
index bd4da649ef..8e876f24cc 100644
--- a/libraries/GCS_MAVLink/GCS_MAVLink.cpp
+++ b/libraries/GCS_MAVLink/GCS_MAVLink.cpp
@@ -36,6 +36,9 @@ AP_HAL::UARTDriver	*mavlink_comm_1_port;
 #if MAVLINK_COMM_NUM_BUFFERS > 2
 AP_HAL::UARTDriver	*mavlink_comm_2_port;
 #endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+AP_HAL::UARTDriver  *mavlink_comm_3_port;
+#endif
 
 mavlink_system_t mavlink_system = {7,1};
 
@@ -100,6 +103,11 @@ uint8_t comm_receive_ch(mavlink_channel_t chan)
 	case MAVLINK_COMM_2:
 		data = mavlink_comm_2_port->read();
 		break;
+#endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+    case MAVLINK_COMM_3:
+        data = mavlink_comm_3_port->read();
+        break;
 #endif
 	default:
 		break;
@@ -128,6 +136,11 @@ uint16_t comm_get_txspace(mavlink_channel_t chan)
 	case MAVLINK_COMM_2:
 		ret = mavlink_comm_2_port->txspace();
 		break;
+#endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+    case MAVLINK_COMM_3:
+        ret = mavlink_comm_3_port->txspace();
+        break;
 #endif
 	default:
 		break;
@@ -159,6 +172,11 @@ uint16_t comm_get_available(mavlink_channel_t chan)
 	case MAVLINK_COMM_2:
 		bytes = mavlink_comm_2_port->available();
 		break;
+#endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+    case MAVLINK_COMM_3:
+        bytes = mavlink_comm_3_port->available();
+        break;
 #endif
 	default:
 		break;
@@ -185,6 +203,11 @@ void comm_send_buffer(mavlink_channel_t chan, const uint8_t *buf, uint8_t len)
 	case MAVLINK_COMM_2:
 		mavlink_comm_2_port->write(buf, len);
 		break;
+#endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+    case MAVLINK_COMM_3:
+        mavlink_comm_3_port->write(buf, len);
+        break;
 #endif
 	default:
 		break;
diff --git a/libraries/GCS_MAVLink/GCS_MAVLink.h b/libraries/GCS_MAVLink/GCS_MAVLink.h
index 1008334b3b..7886e14020 100644
--- a/libraries/GCS_MAVLink/GCS_MAVLink.h
+++ b/libraries/GCS_MAVLink/GCS_MAVLink.h
@@ -26,8 +26,8 @@
 // only two telemetry ports on APM1/APM2
 #define MAVLINK_COMM_NUM_BUFFERS 2
 #else
-// allow three telemetry ports on other boards
-#define MAVLINK_COMM_NUM_BUFFERS 3
+// allow four telemetry ports on other boards
+#define MAVLINK_COMM_NUM_BUFFERS 4
 #endif
 
 /*
@@ -61,6 +61,10 @@ extern AP_HAL::UARTDriver	*mavlink_comm_1_port;
 extern AP_HAL::UARTDriver	*mavlink_comm_2_port;
 #endif
 
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+extern AP_HAL::UARTDriver   *mavlink_comm_3_port;
+#endif
+
 /// MAVLink system definition
 extern mavlink_system_t mavlink_system;
 
@@ -82,6 +86,11 @@ static inline void comm_send_ch(mavlink_channel_t chan, uint8_t ch)
 	case MAVLINK_COMM_2:
 		mavlink_comm_2_port->write(ch);
 		break;
+#endif
+#if MAVLINK_COMM_NUM_BUFFERS > 3
+    case MAVLINK_COMM_3:
+        mavlink_comm_3_port->write(ch);
+        break;
 #endif
 	default:
 		break;