diff --git a/Makefile b/Makefile
index 16d1eee..d58ad0e 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,7 @@ prep-avr:
 
 prep-esp32:
 	arduino-cli core update-index --config-file arduino-cli.yaml
-	arduino-cli core install esp32:esp32 --config-file arduino-cli.yaml
+	arduino-cli core install esp32:esp32@$(ESP_IDF_VER) --config-file arduino-cli.yaml
 	arduino-cli lib install "Adafruit SSD1306"
 	arduino-cli lib install "XPowersLib"
 	arduino-cli lib install "Crypto"