diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index cff21173f79..ac6707f9316 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -3,6 +3,7 @@
 
 // tidy-alphabetical-start
 #![recursion_limit = "256"]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cell::Cell;