diff --git a/board/scarlet/board.h b/board/scarlet/board.h
index eabe1c3bd9..6ea473139e 100644
--- a/board/scarlet/board.h
+++ b/board/scarlet/board.h
@@ -25,6 +25,7 @@
 #define CONFIG_SPI
 #define CONFIG_SPI_MASTER
 #define CONFIG_STM_HWTIMER32
+#define CONFIG_STM32_CLOCK_LSE
 #define CONFIG_SWITCH
 #define CONFIG_WATCHDOG_HELP