diff --git a/src/tools/rustc-std-workspace-core/Cargo.toml b/src/tools/rustc-std-workspace-core/Cargo.toml
index f000d634e1943..d527ce12bc3a1 100644
--- a/src/tools/rustc-std-workspace-core/Cargo.toml
+++ b/src/tools/rustc-std-workspace-core/Cargo.toml
@@ -6,6 +6,7 @@ license = 'MIT/Apache-2.0'
 description = """
 Hack for the compiler's own build system
 """
+edition = "2018"
 
 [lib]
 path = "lib.rs"
diff --git a/src/tools/rustc-std-workspace-core/lib.rs b/src/tools/rustc-std-workspace-core/lib.rs
index e2946fe2a97f1..99d51bc2d56ac 100644
--- a/src/tools/rustc-std-workspace-core/lib.rs
+++ b/src/tools/rustc-std-workspace-core/lib.rs
@@ -1,6 +1,5 @@
 #![feature(no_core)]
 #![no_core]
-
-extern crate core;
+#![deny(rust_2018_idioms)]
 
 pub use core::*;