diff --git a/keyboards/lets_split/readme.md b/keyboards/lets_split/readme.md
index 6e296737a2..a63ce59070 100644
--- a/keyboards/lets_split/readme.md
+++ b/keyboards/lets_split/readme.md
@@ -74,6 +74,10 @@ not be very difficult to adapt it to support more if required.
 Flashing
 --------
 
+From the keymap directory run `make SUBPROJECT-KEYMAP-avrdude` for automatic serial port resolution and flashing.
+
+Example: `make rev2-serial-avrdude`
+
 If you define `EE_HANDS` in your `config.h`, you will need to set the
 EEPROM for the left and right halves. The EEPROM is used to store whether the
 half is left handed or right handed. This makes it so that the same firmware
diff --git a/keyboards/lets_split/rules.mk b/keyboards/lets_split/rules.mk
index 1aee5313c1..0dc5491302 100644
--- a/keyboards/lets_split/rules.mk
+++ b/keyboards/lets_split/rules.mk
@@ -73,3 +73,13 @@ USE_I2C ?= yes
 SLEEP_LED_ENABLE ?= no    # Breathing sleep LED during USB suspend
 
 CUSTOM_MATRIX = yes
+
+avrdude: build
+	ls /dev/tty* > /tmp/1; \
+	echo "Reset your Pro Micro then hit any key to continue..."; \
+	read -n 1 -s; \
+	ls /dev/tty* > /tmp/2; \
+	USB=`diff /tmp/1 /tmp/2 | grep '>' | sed -e 's/> //'`; \
+	avrdude -p $(MCU) -c avr109 -P $$USB -U flash:w:$(BUILD_DIR)/$(TARGET).hex
+
+.PHONY: avrdude