diff --git a/left/src/main.c b/left/src/main.c
index 9f03baf..0edd35a 100644
--- a/left/src/main.c
+++ b/left/src/main.c
@@ -2,6 +2,7 @@
 #include "init_clock.h"
 #include "init_peripherals.h"
 #include "bootloader.h"
+#include <stdio.h>
 
 DEFINE_BOOTLOADER_CONFIG_AREA(I2C_ADDRESS_LEFT_KEYBOARD_HALF_BOOTLOADER)