diff --git a/klippy/extras/tmc_uart.py b/klippy/extras/tmc_uart.py
index 85be0149..fe51303e 100644
--- a/klippy/extras/tmc_uart.py
+++ b/klippy/extras/tmc_uart.py
@@ -1,6 +1,6 @@
 # Helper code for communicating with TMC stepper drivers via UART
 #
-# Copyright (C) 2018-2019  Kevin O'Connor <kevin@koconnor.net>
+# Copyright (C) 2018-2021  Kevin O'Connor <kevin@koconnor.net>
 #
 # This file may be distributed under the terms of the GNU GPLv3 license.
 import logging
@@ -16,7 +16,7 @@ class MCU_analog_mux:
         self.cmd_queue = cmd_queue
         ppins = mcu.get_printer().lookup_object("pins")
         select_pin_params = [ppins.lookup_pin(spd, can_invert=True)
-                             for spd in select_pins_desc.split(',')]
+                             for spd in select_pins_desc]
         self.oids = [self.mcu.create_oid() for pp in select_pin_params]
         self.pins = [pp['pin'] for pp in select_pin_params]
         self.pin_values = tuple([-1 for pp in select_pin_params])
@@ -32,7 +32,7 @@ class MCU_analog_mux:
     def get_instance_id(self, select_pins_desc):
         ppins = self.mcu.get_printer().lookup_object("pins")
         select_pin_params = [ppins.parse_pin(spd, can_invert=True)
-                             for spd in select_pins_desc.split(',')]
+                             for spd in select_pins_desc]
         for pin_params in select_pin_params:
             if pin_params['chip'] != self.mcu:
                 raise self.mcu.get_printer().config_error(
@@ -188,8 +188,8 @@ class MCU_TMC_uart_bitbang:
 # Lookup a (possibly shared) tmc uart
 def lookup_tmc_uart_bitbang(config, max_addr):
     ppins = config.get_printer().lookup_object("pins")
-    rx_pin_params = ppins.lookup_pin(
-        config.get('uart_pin'), can_pullup=True, share_type="tmc_uart_rx")
+    rx_pin_params = ppins.lookup_pin(config.get('uart_pin'), can_pullup=True,
+                                     share_type="tmc_uart_rx")
     tx_pin_desc = config.get('tx_pin', None)
     if tx_pin_desc is None:
         tx_pin_params = rx_pin_params
@@ -197,7 +197,7 @@ def lookup_tmc_uart_bitbang(config, max_addr):
         tx_pin_params = ppins.lookup_pin(tx_pin_desc, share_type="tmc_uart_tx")
     if rx_pin_params['chip'] is not tx_pin_params['chip']:
         raise ppins.error("TMC uart rx and tx pins must be on the same mcu")
-    select_pins_desc = config.get('select_pins', None)
+    select_pins_desc = config.getlist('select_pins', None)
     addr = config.getint('uart_address', 0, minval=0, maxval=max_addr)
     mcu_uart = rx_pin_params.get('class')
     if mcu_uart is None: