diff --git a/stm-firmware/main.c b/stm-firmware/main.c
index 7e79ad8..f508952 100644
--- a/stm-firmware/main.c
+++ b/stm-firmware/main.c
@@ -58,7 +58,7 @@ static void setup_nvic_priorities(void)
 }
 
 FATFS fs;
-FATFS * const fs_ptr = &fs;
+#define fs_ptr (&fs)
 
 static inline void uart_gpio_config(void)
 {