diff --git a/ports/atmel-samd/boards/hallowing_m4_express/board.c b/ports/atmel-samd/boards/hallowing_m4_express/board.c
index 6bb2a591f0..5d1ef6d9be 100644
--- a/ports/atmel-samd/boards/hallowing_m4_express/board.c
+++ b/ports/atmel-samd/boards/hallowing_m4_express/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA01, &pin_PA00, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PA01, &pin_PA00, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/monster_m4sk/board.c b/ports/atmel-samd/boards/monster_m4sk/board.c
index 2377f4a9da..40141ca157 100644
--- a/ports/atmel-samd/boards/monster_m4sk/board.c
+++ b/ports/atmel-samd/boards/monster_m4sk/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA12, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA12, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/openbook_m4/board.c b/ports/atmel-samd/boards/openbook_m4/board.c
index 2d9b316474..85a5888799 100644
--- a/ports/atmel-samd/boards/openbook_m4/board.c
+++ b/ports/atmel-samd/boards/openbook_m4/board.c
@@ -55,7 +55,7 @@ uint8_t stop_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pewpew_m4/board.c b/ports/atmel-samd/boards/pewpew_m4/board.c
index 5f5a01e48e..1872d18763 100644
--- a/ports/atmel-samd/boards/pewpew_m4/board.c
+++ b/ports/atmel-samd/boards/pewpew_m4/board.c
@@ -97,7 +97,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PA13, &pin_PA15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pybadge/board.c b/ports/atmel-samd/boards/pybadge/board.c
index f3ac7176ab..3725f0ec34 100644
--- a/ports/atmel-samd/boards/pybadge/board.c
+++ b/ports/atmel-samd/boards/pybadge/board.c
@@ -72,7 +72,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pybadge_airlift/board.c b/ports/atmel-samd/boards/pybadge_airlift/board.c
index 061f3d7772..fbb4441f0e 100644
--- a/ports/atmel-samd/boards/pybadge_airlift/board.c
+++ b/ports/atmel-samd/boards/pybadge_airlift/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pygamer/board.c b/ports/atmel-samd/boards/pygamer/board.c
index 8c6fbca065..b364ffccff 100644
--- a/ports/atmel-samd/boards/pygamer/board.c
+++ b/ports/atmel-samd/boards/pygamer/board.c
@@ -72,7 +72,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/atmel-samd/boards/pygamer_advance/board.c b/ports/atmel-samd/boards/pygamer_advance/board.c
index ff2da34a26..a138c7e504 100644
--- a/ports/atmel-samd/boards/pygamer_advance/board.c
+++ b/ports/atmel-samd/boards/pygamer_advance/board.c
@@ -50,7 +50,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB12, NULL);
+    common_hal_busio_spi_construct(spi, &pin_PB13, &pin_PB12, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/nrf/boards/clue_nrf52840_express/board.c b/ports/nrf/boards/clue_nrf52840_express/board.c
index c118fe92f1..abc4e3cfae 100644
--- a/ports/nrf/boards/clue_nrf52840_express/board.c
+++ b/ports/nrf/boards/clue_nrf52840_express/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/nrf/boards/ohs2020_badge/board.c b/ports/nrf/boards/ohs2020_badge/board.c
index 189f7acdf2..457edf44a5 100644
--- a/ports/nrf/boards/ohs2020_badge/board.c
+++ b/ports/nrf/boards/ohs2020_badge/board.c
@@ -49,7 +49,7 @@ uint8_t display_init_sequence[] = {
 
 void board_init(void) {
     busio_spi_obj_t* spi = &displays[0].fourwire_bus.inline_bus;
-    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, NULL);
+    common_hal_busio_spi_construct(spi, &pin_P0_14, &pin_P0_15, mp_const_none);
     common_hal_busio_spi_never_reset(spi);
 
     displayio_fourwire_obj_t* bus = &displays[0].fourwire_bus;
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c
index 639bbcdd05..8e1d73bf0e 100644
--- a/ports/nrf/common-hal/busio/SPI.c
+++ b/ports/nrf/common-hal/busio/SPI.c
@@ -143,7 +143,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
     self->clock_pin_number = clock->number;
     claim_pin(clock);
 
-    if (mosi != (mcu_pin_obj_t*)&mp_const_none_obj) {
+    if (mosi != mp_const_none) {
         config.mosi_pin = mosi->number;
         self->MOSI_pin_number = mosi->number;
         claim_pin(mosi);
@@ -151,7 +151,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
         self->MOSI_pin_number = NO_PIN;
     }
 
-    if (miso != (mcu_pin_obj_t*)&mp_const_none_obj) {
+    if (miso != mp_const_none) {
         config.miso_pin = miso->number;
         self->MISO_pin_number = mosi->number;
         claim_pin(miso);
diff --git a/ports/nrf/peripherals/nrf/nrf52840/power.c b/ports/nrf/peripherals/nrf/nrf52840/power.c
index 794872c5d9..d64c536bb3 100644
--- a/ports/nrf/peripherals/nrf/nrf52840/power.c
+++ b/ports/nrf/peripherals/nrf/nrf52840/power.c
@@ -25,16 +25,26 @@
  */
 
 #include "nrfx.h"
-#include "nrfx_nvmc.h"
+#include "hal/nrf_nvmc.h"
 
 void nrf_peripherals_power_init(void) {
     // Set GPIO reference voltage to 3.3V if it isn't already. REGOUT0 will get reset to 0xfffffff
     // if flash is erased, which sets the default to 1.8V
     // This matters only when "high voltage mode" is enabled, which is true on the PCA10059,
     // and might be true on other boards.
-    if (NRF_UICR->REGOUT0 == 0xffffffff) {
-        nrfx_nvmc_word_write((uint32_t) &NRF_UICR->REGOUT0, UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos);
-        // Must reset to make enable change.
+    if (NRF_UICR->REGOUT0 == 0xffffffff && NRF_POWER->MAINREGSTATUS & 1) {
+        // Expand what nrf_nvmc_word_write() did.
+        // It's missing from nrfx V2.0.0, and nrfx_nvmc_word_write() does bounds
+        // checking which prevents writes to UICR.
+        // Reported: https://devzone.nordicsemi.com/f/nordic-q-a/57243/nrfx_nvmc-h-api-cannot-write-to-uicr
+        NRF_NVMC->CONFIG = NRF_NVMC_MODE_WRITE;
+        while (!(NRF_NVMC->READY & NVMC_READY_READY_Msk)) {}
+        NRF_UICR->REGOUT0 = UICR_REGOUT0_VOUT_3V3 << UICR_REGOUT0_VOUT_Pos;
+        __DMB();
+        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {}
+        NRF_NVMC->CONFIG = NRF_NVMC_MODE_READONLY;
+
+        // Must reset to enable change.
         NVIC_SystemReset();
     }
 }