diff --git a/.gitignore b/.gitignore
index 96ef6c0..ff0d847 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /target
+/.vscode
 Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
index 61bce0a..29c93da 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "avr-config"
-version = "2.0.1"
+version = "2.0.2"
 authors = ["Dylan McKay <me@dylanmckay.io>"]
 edition = "2018"
 
diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..56e558c
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,4 @@
+fn main() {
+    #[cfg(feature = "cpu-frequency")]
+    println!("cargo:rerun-if-env-changed=AVR_CPU_FREQUENCY_HZ");
+}