diff --git a/README.md b/README.md
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+++ b/README.md
@@ -1,4 +1,4 @@
-# WIP: tzf's Rust port. [![Rust](https://github.com/ringsaturn/tzf-rs/actions/workflows/rust.yml/badge.svg)](https://github.com/ringsaturn/tzf-rs/actions/workflows/rust.yml) [![Documentation](https://docs.rs/tzf-rs/badge.svg)](https://docs.rs/tzf-rs)
+# WIP: tzf's Rust port. [![Rust](https://github.com/ringsaturn/tzf-rs/actions/workflows/rust.yml/badge.svg)](https://github.com/ringsaturn/tzf-rs/actions/workflows/rust.yml) [![Documentation](https://docs.rs/tzf-rs/badge.svg)](https://docs.rs/tzf-rs) [![codecov](https://codecov.io/gh/ringsaturn/tzf-rs/branch/main/graph/badge.svg?token=NQFIP9DD86)](https://codecov.io/gh/ringsaturn/tzf-rs)
 
 - Documents: <https://docs.rs/tzf-rs>
 - Original Go repo: <https://github.com/ringsaturn/tzf>