diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index 410bd06850e75..5cece569903c7 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -12,7 +12,9 @@ use rustc_hir::{intravisit, HirId};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::LevelSource;
 use rustc_middle::lint::LintDiagnosticBuilder;
-use rustc_middle::lint::{struct_lint_level, LintLevelMap, LintLevelSets, LintSet, LintLevelSource};
+use rustc_middle::lint::{
+    struct_lint_level, LintLevelMap, LintLevelSets, LintLevelSource, LintSet,
+};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::{builtin, Level, Lint, LintId};
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 2dbb84970d106..d1a7e89734d2a 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -45,6 +45,7 @@ impl LintLevelSource {
     }
 }
 
+/// A tuple of a lint level and its source.
 pub type LevelSource = (Level, LintLevelSource);
 
 pub struct LintLevelSets {