diff --git a/src/tools/build-manifest/Cargo.toml b/src/tools/build-manifest/Cargo.toml
index 844b7aad72fd..0fda887ea61f 100644
--- a/src/tools/build-manifest/Cargo.toml
+++ b/src/tools/build-manifest/Cargo.toml
@@ -2,6 +2,7 @@
 name = "build-manifest"
 version = "0.1.0"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
 
 [dependencies]
 toml = "0.4"
diff --git a/src/tools/build-manifest/src/main.rs b/src/tools/build-manifest/src/main.rs
index 4ca285b9b1db..5e8559725f13 100644
--- a/src/tools/build-manifest/src/main.rs
+++ b/src/tools/build-manifest/src/main.rs
@@ -1,4 +1,6 @@
-extern crate toml;
+#![deny(rust_2018_idioms)]
+
+use toml;
 #[macro_use]
 extern crate serde_derive;