diff --git a/compiler/rustc_passes/src/hir_id_validator.rs b/compiler/rustc_passes/src/hir_id_validator.rs
index 212ea9e57a3..3bb8c0bb48c 100644
--- a/compiler/rustc_passes/src/hir_id_validator.rs
+++ b/compiler/rustc_passes/src/hir_id_validator.rs
@@ -103,7 +103,7 @@ fn check<F: FnOnce(&mut HirIdValidator<'a, 'hir>)>(&mut self, owner: LocalDefId,
             self.error(|| {
                 format!(
                     "ItemLocalIds not assigned densely in {}. \
-                Max ItemLocalId = {}, missing IDs = {:?}; seens IDs = {:?}",
+                Max ItemLocalId = {}, missing IDs = {:#?}; seens IDs = {:#?}",
                     self.hir_map.def_path(owner).to_string_no_crate_verbose(),
                     max,
                     missing_items,