diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 9b3884f229d7a..fedc7f84c0f52 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -189,9 +189,9 @@ def get_alt_function(self, mcu, pin, function):
                     return 0
             return None
 
-        if function and function.endswith("_RTS") and (
+        if function and (function.endswith("_RTS") or function.endswith("_CTS_GPIO")) and (
                 function.startswith('USART') or function.startswith('UART')):
-            # we do software RTS
+            # we do software RTS and can do either software CTS or hardware CTS
             return None
 
         for label in self.af_labels:
@@ -1891,6 +1891,8 @@ def write_UART_config(self, f):
             rts_line_name = dev + '_RTS'
             rts_line = self.make_line(rts_line_name)
             cts_line = self.make_line(dev + '_CTS')
+            if cts_line == "0":
+                cts_line = self.make_line(dev + '_CTS_GPIO')
             if rts_line != "0":
                 have_rts_cts = True
                 f.write('#define HAL_HAVE_RTSCTS_SERIAL%u\n' % num)
@@ -2927,12 +2929,12 @@ def valid_type(self, ptype, label):
         if ptype == 'OUTPUT' and re.match(r'US?ART\d+_(TXINV|RXINV)', label):
             return True
         m1 = re.match(r'USART(\d+)', ptype)
-        m2 = re.match(r'USART(\d+)_(RX|TX|CTS|RTS)', label)
+        m2 = re.match(r'USART(\d+)_(RX|TX|CTS|RTS|CTS_GPIO)', label)
         if (m1 and not m2) or (m2 and not m1) or (m1 and m1.group(1) != m2.group(1)):
             '''usart numbers need to match'''
             return False
         m1 = re.match(r'UART(\d+)', ptype)
-        m2 = re.match(r'UART(\d+)_(RX|TX|CTS|RTS)', label)
+        m2 = re.match(r'UART(\d+)_(RX|TX|CTS|RTS|CTS_GPIO)', label)
         if (m1 and not m2) or (m2 and not m1) or (m1 and m1.group(1) != m2.group(1)):
             '''uart numbers need to match'''
             return False