diff --git a/atmel-samd/boards/metro_m0_flash/mpconfigboard.h b/atmel-samd/boards/metro_m0_flash/mpconfigboard.h
index b9d2f5f025..a4e1e3fc54 100644
--- a/atmel-samd/boards/metro_m0_flash/mpconfigboard.h
+++ b/atmel-samd/boards/metro_m0_flash/mpconfigboard.h
@@ -4,6 +4,7 @@
 #define MICROPY_HW_BOARD_NAME "Adafruit Metro M0 with Flash (Experimental)"
 #define MICROPY_HW_MCU_NAME "samd21g18"
 
+#define MICROPY_HW_LED_MSC  PIN_PA17
 #define MICROPY_HW_LED_TX   PIN_PA27
 #define MICROPY_HW_LED_RX   PIN_PB03
 
diff --git a/atmel-samd/spi_flash.c b/atmel-samd/spi_flash.c
index 5424ee6ea5..fef630eff1 100644
--- a/atmel-samd/spi_flash.c
+++ b/atmel-samd/spi_flash.c
@@ -198,7 +198,6 @@ static bool copy_block(uint32_t src_address, uint32_t dest_address) {
 
 void spi_flash_init(void) {
     if (!spi_flash_is_initialised) {
-
         struct spi_config config_spi_master;
         spi_get_config_defaults(&config_spi_master);
         config_spi_master.mux_setting = SPI_FLASH_MUX_SETTING;
@@ -218,6 +217,12 @@ void spi_flash_init(void) {
         port_pin_set_config(SPI_FLASH_CS, &pin_conf);
         flash_disable();
 
+        // Activity LED for flash writes.
+        #ifdef MICROPY_HW_LED_MSC
+            port_pin_set_config(MICROPY_HW_LED_MSC, &pin_conf);
+            port_pin_set_output_level(MICROPY_HW_LED_MSC, false);
+        #endif
+
         uint8_t jedec_id_request[4] = {CMD_READ_JEDEC_ID, 0x00, 0x00, 0x00};
         uint8_t response[4] = {0x00, 0x00, 0x00, 0x00};
         flash_enable();
@@ -377,6 +382,9 @@ static void spi_flash_flush_keep_cache(bool keep_cache) {
     if (current_sector == NO_SECTOR_LOADED) {
         return;
     }
+    #ifdef MICROPY_HW_LED_MSC
+        port_pin_set_output_level(MICROPY_HW_LED_MSC, true);
+    #endif
     // If we've cached to the flash itself flush from there.
     if (ram_cache == NULL) {
         flush_scratch_flash();
@@ -384,6 +392,9 @@ static void spi_flash_flush_keep_cache(bool keep_cache) {
         flush_ram_cache(keep_cache);
     }
     current_sector = NO_SECTOR_LOADED;
+    #ifdef MICROPY_HW_LED_MSC
+        port_pin_set_output_level(MICROPY_HW_LED_MSC, false);
+    #endif
 }
 
 // External flash function used. If called externally we assume we won't need