diff --git a/clippy_lints/src/methods.rs b/clippy_lints/src/methods.rs
index 6850ef2f8..33c532e17 100644
--- a/clippy_lints/src/methods.rs
+++ b/clippy_lints/src/methods.rs
@@ -1885,7 +1885,7 @@ fn lint_chars_last_cmp_with_unwrap<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, info: &
 }
 
 /// lint for length-1 `str`s for methods in `PATTERN_METHODS`
-fn lint_single_char_pattern<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, arg: &'tcx hir::Expr) {
+fn lint_single_char_pattern<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, _expr: &'tcx hir::Expr, arg: &'tcx hir::Expr) {
     if let Some((Constant::Str(r), _)) = constant(cx, cx.tables, arg) {
         if r.len() == 1 {
             let c = r.chars().next().unwrap();