diff --git a/ports/atmel-samd/common-hal/busio/UART.c b/ports/atmel-samd/common-hal/busio/UART.c
index c4e70787a8..fb9968605f 100644
--- a/ports/atmel-samd/common-hal/busio/UART.c
+++ b/ports/atmel-samd/common-hal/busio/UART.c
@@ -65,7 +65,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t tx_pinmux = 0;
     uint8_t tx_pad = 255; // Unset pad
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert == true)) {
+    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
 
diff --git a/ports/cxd56/common-hal/busio/UART.c b/ports/cxd56/common-hal/busio/UART.c
index 688a355424..3ed9809529 100644
--- a/ports/cxd56/common-hal/busio/UART.c
+++ b/ports/cxd56/common-hal/busio/UART.c
@@ -60,7 +60,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     mp_float_t timeout, uint16_t receiver_buffer_size) {
     struct termios tio;
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert == true)) {
+    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }
     
diff --git a/ports/mimxrt10xx/common-hal/busio/UART.c b/ports/mimxrt10xx/common-hal/busio/UART.c
index 3609a99982..4fd7afecbc 100644
--- a/ports/mimxrt10xx/common-hal/busio/UART.c
+++ b/ports/mimxrt10xx/common-hal/busio/UART.c
@@ -123,41 +123,38 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
       // For IMXRT the RTS pin is used for RS485 direction
       rts = rs485_dir;
     }
-    else
-      {
-        if (rs485_invert == true) {
-          mp_raise_ValueError(translate("RS485 inversion specified when not in RS485 mode"));
-        }
+    else {
+      if (rs485_invert) {
+        mp_raise_ValueError(translate("RS485 inversion specified when not in RS485 mode"));
       }
+    }
 
     // Now check for RTS/CTS (or overloaded RS485 direction) pin(s)
     const uint32_t rts_count = sizeof(mcu_uart_rts_list) / sizeof(mcu_periph_obj_t);
     const uint32_t cts_count = sizeof(mcu_uart_cts_list) / sizeof(mcu_periph_obj_t);
 
     if (rts != mp_const_none) {
-      for (uint32_t i=0; i < rts_count; ++i)
-        {
-          if (mcu_uart_rts_list[i].bank_idx == self->rx_pin->bank_idx) {
-            if (mcu_uart_rts_list[i].pin == rts) {
-              self->rts_pin = &mcu_uart_rts_list[i];
-              break;
-            }
+      for (uint32_t i=0; i < rts_count; ++i) {
+        if (mcu_uart_rts_list[i].bank_idx == self->rx_pin->bank_idx) {
+          if (mcu_uart_rts_list[i].pin == rts) {
+            self->rts_pin = &mcu_uart_rts_list[i];
+            break;
           }
         }
+      }
       if (self->rts_pin == NULL)
         mp_raise_ValueError(translate("Selected RTS pin not valid"));
     }
 
     if (cts != mp_const_none) {
-      for (uint32_t i=0; i < cts_count; ++i)
-        {
-          if (mcu_uart_cts_list[i].bank_idx == self->rx_pin->bank_idx) {
-            if (mcu_uart_cts_list[i].pin == cts) {
-              self->cts_pin = &mcu_uart_cts_list[i];
-              break;
-            }
+      for (uint32_t i=0; i < cts_count; ++i) {
+        if (mcu_uart_cts_list[i].bank_idx == self->rx_pin->bank_idx) {
+          if (mcu_uart_cts_list[i].pin == cts) {
+            self->cts_pin = &mcu_uart_cts_list[i];
+            break;
           }
         }
+      }
       if (self->cts_pin == NULL)
         mp_raise_ValueError(translate("Selected CTS pin not valid"));
     }
@@ -192,7 +189,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t modir = (self->uart->MODIR) & ~(LPUART_MODIR_TXRTSPOL_MASK | LPUART_MODIR_TXRTSE_MASK);
     if (rs485_dir != mp_const_none) {
       modir |= LPUART_MODIR_TXRTSE_MASK;
-      if ( rs485_invert == true )
+      if (rs485_invert)
         modir |= LPUART_MODIR_TXRTSPOL_MASK;
     }
     self->uart->MODIR = modir;
diff --git a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/periph.h b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/periph.h
index a791aa2942..d6d4895371 100644
--- a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/periph.h
+++ b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1011/periph.h
@@ -36,8 +36,8 @@ extern const mcu_periph_obj_t mcu_spi_miso_list[4];
 
 extern const mcu_periph_obj_t mcu_uart_rx_list[9];
 extern const mcu_periph_obj_t mcu_uart_tx_list[9];
-const mcu_periph_obj_t mcu_uart_rts_list[4];
-const mcu_periph_obj_t mcu_uart_cts_list[4];                                               
+extern const mcu_periph_obj_t mcu_uart_rts_list[4];
+extern const mcu_periph_obj_t mcu_uart_cts_list[4];
 
 extern const mcu_pwm_obj_t mcu_pwm_list[20];
 
diff --git a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1062/periph.h b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1062/periph.h
index dbda2edb19..45b92f2473 100644
--- a/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1062/periph.h
+++ b/ports/mimxrt10xx/peripherals/mimxrt10xx/MIMXRT1062/periph.h
@@ -36,8 +36,8 @@ extern const mcu_periph_obj_t mcu_spi_miso_list[8];
 
 extern const mcu_periph_obj_t mcu_uart_rx_list[18];
 extern const mcu_periph_obj_t mcu_uart_tx_list[18];
-const mcu_periph_obj_t mcu_uart_rts_list[9];
-const mcu_periph_obj_t mcu_uart_cts_list[9];
+extern const mcu_periph_obj_t mcu_uart_rts_list[9];
+extern const mcu_periph_obj_t mcu_uart_cts_list[9];
 
 extern const mcu_pwm_obj_t mcu_pwm_list[67];
 
diff --git a/ports/nrf/common-hal/busio/UART.c b/ports/nrf/common-hal/busio/UART.c
index c422a187f6..933faf17b8 100644
--- a/ports/nrf/common-hal/busio/UART.c
+++ b/ports/nrf/common-hal/busio/UART.c
@@ -135,7 +135,7 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     uint32_t baudrate, uint8_t bits, uart_parity_t parity, uint8_t stop,
     mp_float_t timeout, uint16_t receiver_buffer_size) {
 
-    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert == true)) {
+    if ((rts != mp_const_none) || (cts != mp_const_none) || (rs485_dir != mp_const_none) || (rs485_invert)) {
         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
     }