diff --git a/libraries/AP_HAL_SITL/SITL_State.h b/libraries/AP_HAL_SITL/SITL_State.h
index a73baf28bd..18838c0cda 100644
--- a/libraries/AP_HAL_SITL/SITL_State.h
+++ b/libraries/AP_HAL_SITL/SITL_State.h
@@ -71,13 +71,14 @@ public:
     uint16_t current2_pin_value;  // pin 14
 
     // paths for UART devices
-    const char *_uart_path[6] {
+    const char *_uart_path[7] {
         "tcp:0:wait",
         "GPS1",
         "tcp:2",
         "tcp:3",
         "GPS2",
         "tcp:5",
+        "tcp:6",
     };
     
 private:
diff --git a/libraries/AP_HAL_SITL/SITL_cmdline.cpp b/libraries/AP_HAL_SITL/SITL_cmdline.cpp
index ba8b04e631..a6ae629d21 100644
--- a/libraries/AP_HAL_SITL/SITL_cmdline.cpp
+++ b/libraries/AP_HAL_SITL/SITL_cmdline.cpp
@@ -294,6 +294,7 @@ void SITL_State::_parse_command_line(int argc, char * const argv[])
         case CMDLINE_UARTD:
         case CMDLINE_UARTE:
         case CMDLINE_UARTF:
+        case CMDLINE_UARTG:
             _uart_path[opt - CMDLINE_UARTA] = gopt.optarg;
             break;
         case CMDLINE_RTSCTS:
diff --git a/libraries/AP_HAL_SITL/UARTDriver.cpp b/libraries/AP_HAL_SITL/UARTDriver.cpp
index f605bc2c37..15161636d8 100644
--- a/libraries/AP_HAL_SITL/UARTDriver.cpp
+++ b/libraries/AP_HAL_SITL/UARTDriver.cpp
@@ -50,6 +50,10 @@ bool UARTDriver::_console;
 
 void UARTDriver::begin(uint32_t baud, uint16_t rxSpace, uint16_t txSpace)
 {
+    if (_portNumber > ARRAY_SIZE(_sitlState->_uart_path)) {
+        AP_HAL::panic("port number out of range; you may need to extend _sitlState->_uart_path");
+    }
+
     const char *path = _sitlState->_uart_path[_portNumber];
 
     // default to 1MBit