diff --git a/cargo/.cargo/config.toml b/cargo/.cargo/config.toml
index e0f3b1f..1197949 100644
--- a/cargo/.cargo/config.toml
+++ b/cargo/.cargo/config.toml
@@ -22,6 +22,7 @@ build-std = ["core", "alloc", "panic_abort"]
 
 [env]
 # Note: these variables are not used when using pio builder (`cargo build --features pio`)
+MCU={{ mcu }}
 {%- if espidfver == "v4.4" %}
 ESP_IDF_VERSION = "v4.4.6"
 {% elsif espidfver == "v5.1" %}