diff --git a/ports/stm/boards/feather_stm32f405_express/mpconfigboard.h b/ports/stm/boards/feather_stm32f405_express/mpconfigboard.h
index e002bbed1f..8f8e245665 100644
--- a/ports/stm/boards/feather_stm32f405_express/mpconfigboard.h
+++ b/ports/stm/boards/feather_stm32f405_express/mpconfigboard.h
@@ -35,7 +35,7 @@
 #define MICROPY_HW_NEOPIXEL (&pin_PC00)
 
 #define BOARD_OSC_DIV (12)
-
+#define HSE_VALUE       ((uint32_t)12000000U)
 #define BOARD_HAS_LOW_SPEED_CRYSTAL (1)
 
 // On-board flash