diff --git a/Marlin/src/HAL/STM32/MarlinSerial.h b/Marlin/src/HAL/STM32/MarlinSerial.h
index 290fdce9ee..d971ff704b 100644
--- a/Marlin/src/HAL/STM32/MarlinSerial.h
+++ b/Marlin/src/HAL/STM32/MarlinSerial.h
@@ -52,3 +52,9 @@ extern MarlinSerial MSerial2;
 extern MarlinSerial MSerial3;
 extern MarlinSerial MSerial4;
 extern MarlinSerial MSerial5;
+extern MarlinSerial MSerial6;
+extern MarlinSerial MSerial7;
+extern MarlinSerial MSerial8;
+extern MarlinSerial MSerial9;
+extern MarlinSerial MSerial10;
+extern MarlinSerial MSerialLP1;