diff --git a/src/librustc_fs_util/Cargo.toml b/src/librustc_fs_util/Cargo.toml
index e40b44204b3..47918643f31 100644
--- a/src/librustc_fs_util/Cargo.toml
+++ b/src/librustc_fs_util/Cargo.toml
@@ -2,6 +2,7 @@
 authors = ["The Rust Project Developers"]
 name = "rustc_fs_util"
 version = "0.0.0"
+edition = "2018"
 
 [lib]
 name = "rustc_fs_util"
diff --git a/src/librustc_fs_util/lib.rs b/src/librustc_fs_util/lib.rs
index 74ff121f803..340681d65c3 100644
--- a/src/librustc_fs_util/lib.rs
+++ b/src/librustc_fs_util/lib.rs
@@ -1,3 +1,5 @@
+#![deny(rust_2018_idioms)]
+
 use std::path::{Path, PathBuf};
 use std::ffi::CString;
 use std::fs;