diff --git a/ports/atmel-samd/common-hal/microcontroller/Pin.c b/ports/atmel-samd/common-hal/microcontroller/Pin.c
index 5ce077eb86c3..ef1d8fffaa2d 100644
--- a/ports/atmel-samd/common-hal/microcontroller/Pin.c
+++ b/ports/atmel-samd/common-hal/microcontroller/Pin.c
@@ -106,6 +106,10 @@ void reset_all_pins(void) {
 }
 
 void never_reset_pin_number(uint8_t pin_number) {
+    if (pin_number >= PORT_BITS) {
+        return;
+    }
+
     never_reset_pins[GPIO_PORT(pin_number)] |= 1 << GPIO_PIN(pin_number);
 }
 
diff --git a/ports/esp32s2/common-hal/microcontroller/Pin.c b/ports/esp32s2/common-hal/microcontroller/Pin.c
index 03a83cfe6799..546dca848c5b 100644
--- a/ports/esp32s2/common-hal/microcontroller/Pin.c
+++ b/ports/esp32s2/common-hal/microcontroller/Pin.c
@@ -45,6 +45,9 @@ bool apa102_mosi_in_use;
 bool apa102_sck_in_use;
 
 void never_reset_pin_number(gpio_num_t pin_number) {
+    if (pin_number == -1 ) {
+         return;
+    }
     never_reset_pins[pin_number / 32] |= 1 << pin_number % 32;
 }
 
@@ -54,6 +57,9 @@ void common_hal_never_reset_pin(const mcu_pin_obj_t* pin) {
 
 // Mark pin as free and return it to a quiescent state.
 void reset_pin_number(gpio_num_t pin_number) {
+    if (pin_number == -1 ) {
+         return;
+    }
     never_reset_pins[pin_number / 32] &= ~(1 << pin_number % 32);
     in_use[pin_number / 32] &= ~(1 << pin_number % 32);
 
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c
index 380ec27de455..1cf074955f9c 100644
--- a/ports/nrf/common-hal/busio/SPI.c
+++ b/ports/nrf/common-hal/busio/SPI.c
@@ -180,7 +180,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self, const mcu_pin_obj_t *
 
     if (miso != NULL) {
         config.miso_pin = miso->number;
-        self->MISO_pin_number = mosi->number;
+        self->MISO_pin_number = miso->number;
         claim_pin(miso);
     } else {
         self->MISO_pin_number = NO_PIN;
diff --git a/ports/nrf/common-hal/microcontroller/Pin.c b/ports/nrf/common-hal/microcontroller/Pin.c
index d294c1dd5d18..bc7ff831a563 100644
--- a/ports/nrf/common-hal/microcontroller/Pin.c
+++ b/ports/nrf/common-hal/microcontroller/Pin.c
@@ -123,6 +123,9 @@ void reset_pin_number(uint8_t pin_number) {
 
 
 void never_reset_pin_number(uint8_t pin_number) {
+    if (pin_number == NO_PIN) {
+        return;
+    }
     never_reset_pins[nrf_pin_port(pin_number)] |= 1 << nrf_relative_pin_number(pin_number);
 }
 
diff --git a/ports/stm/common-hal/microcontroller/Pin.c b/ports/stm/common-hal/microcontroller/Pin.c
index 9fbdedeade19..99651327030b 100644
--- a/ports/stm/common-hal/microcontroller/Pin.c
+++ b/ports/stm/common-hal/microcontroller/Pin.c
@@ -70,6 +70,10 @@ void reset_all_pins(void) {
 
 // Mark pin as free and return it to a quiescent state.
 void reset_pin_number(uint8_t pin_port, uint8_t pin_number) {
+    if ( pin_number == NO_PIN ) {
+        return;
+    }
+
     if (pin_port == 0x0F) {
         return;
     }
@@ -88,6 +92,9 @@ void reset_pin_number(uint8_t pin_port, uint8_t pin_number) {
 }
 
 void never_reset_pin_number(uint8_t pin_port, uint8_t pin_number) {
+    if ( pin_number == NO_PIN ) {
+        return;
+    }
     never_reset_pins[pin_port] |= 1<<pin_number;
     // Make sure never reset pins are also always claimed
     claimed_pins[pin_port] |= 1<<pin_number;