diff --git a/src/get_serial.c b/src/get_serial.c
index 7bf72e3..04bf77a 100644
--- a/src/get_serial.c
+++ b/src/get_serial.c
@@ -24,6 +24,7 @@
  */
 
 #include <stdint.h>
+#include "pico.h"
 #include "pico/unique_id.h"
 #include "get_serial.h"