diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..43b1bd4
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,9 @@
+[build]
+target = "avr-atmega328p.json"
+
+[unstable]
+build-std = ["core"]
+
+# Cargo versions before 2021-02-23 won't recognize this: https://github.com/rust-lang/cargo/pull/9175
+[env]
+AVR_CPU_FREQUENCY_HZ = 16000000