diff --git a/variants/m5stack_unit_c6l/platformio.ini b/variants/m5stack_unit_c6l/platformio.ini
index ea4d852d65..db958a7df5 100644
--- a/variants/m5stack_unit_c6l/platformio.ini
+++ b/variants/m5stack_unit_c6l/platformio.ini
@@ -43,6 +43,8 @@ build_src_filter = ${M5Stack_Unit_C6L.build_src_filter}
   +<../examples/simple_repeater/*.cpp>
 build_flags =
   ${M5Stack_Unit_C6L.build_flags}
+  -D ARDUINO_USB_CDC_ON_BOOT=1
+  -D ARDUINO_USB_MODE=1
   -D ADVERT_NAME='"Unit C6L Repeater"'
   -D ADVERT_LAT=0.0
   -D ADVERT_LON=0.0
@@ -60,6 +62,8 @@ build_src_filter = ${M5Stack_Unit_C6L.build_src_filter}
   +<../examples/simple_room_server>
 build_flags =
   ${M5Stack_Unit_C6L.build_flags}
+  -D ARDUINO_USB_CDC_ON_BOOT=1
+  -D ARDUINO_USB_MODE=1
   -D ADVERT_NAME='"Unit C6L Room"'
   -D ADVERT_LAT=0.0
   -D ADVERT_LON=0.0