Concurrent programs suffer from data races. To prevent data races, programmers use locks. However, programs can eliminate data races only when they acquire and release correct locks at correct timing. The lock API of C, in which people have developed a large portion of legacy system programs, does not validate the correct use of locks. On the other hand, Rust, a recently developed system programming language, provides a lock API that guarantees the correct use of locks via type checking. This makes rewriting legacy system programs in Rust a promising way to retrofit safety into them. Unfortunately, manual C-to-Rust translation is extremely laborious due to the discrepancies between their lock APIs. Even the state-of-the-art automatic C-to-Rust translator retains the C lock API, expecting developers to replace them with the Rust lock API. In this work, we propose an automatic tool to replace the C lock API with the Rust lock API. It facilitates C-to-Rust translation of concurrent programs with less human effort than the current practice. Our tool consists of a Rust code transformer that takes a lock summary as an input and a static analyzer that efficiently generates precise lock summaries. We show that the transformer is scalable and widely applicable while preserving the semantics; it transforms 66 KLOC in 2.6 seconds and successfully handles 74% of real-world programs. We also show that the analyzer is scalable and precise; it analyzes 66 KLOC in 4.3 seconds. of the Linux kernel will support Rust code [23]. Android and Fuchsia implementations also use RustReimplementing concurrent programs in Rust is, however, labor-intensive if done manually. The discrepancies between the lock APIs of C and Rust hinder programmers from mechanical rewriting. They have to understand the use of the C lock API in original programs and restructure the programs to express the intended logic with the Rust lock API. It poses the necessity for a tool for automatic C-to-Rust translation.The state-of-the-art C-to-Rust translator, C2Rust [58], is still far from alleviating the burden on programmers. The translation of C2Rust is completely syntactic and generates Rust code using the C lock API. Programmers are expected to replace the C lock API in C2Rust-generated code with the Rust lock API for thread safety. While being better than nothing,