diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index 4353a294cc31d..e4a702531442e 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -1,3 +1,4 @@
+#![deny(invalid_codeblock_attributes)]
 //! This library is used to gather all error codes into one place,
 //! the goal being to make their maintenance easier.