diff --git a/ports/nrf/supervisor/port.c b/ports/nrf/supervisor/port.c
index d3c31b51a6..264fb81982 100644
--- a/ports/nrf/supervisor/port.c
+++ b/ports/nrf/supervisor/port.c
@@ -472,3 +472,9 @@ void HardFault_Handler(void) {
         asm("nop;");
     }
 }
+
+#if CIRCUITPY_ALARM
+// in case boards/xxx/board.c does not provide board_deinit()
+MP_WEAK void board_deinit(void) {
+}
+#endif