diff --git a/Marlin/serial.h b/Marlin/serial.h
index 62e06c9892..b57e7b1b67 100644
--- a/Marlin/serial.h
+++ b/Marlin/serial.h
@@ -23,6 +23,8 @@
 #ifndef __SERIAL_H__
 #define __SERIAL_H__
 
+#include "MarlinConfig.h"
+
 #ifdef USBCON
   #include "HardwareSerial.h"
   #if ENABLED(BLUETOOTH)