diff --git a/clippy_lints/src/doc.rs b/clippy_lints/src/doc.rs
index a00361e6062..16173580fd4 100644
--- a/clippy_lints/src/doc.rs
+++ b/clippy_lints/src/doc.rs
@@ -628,9 +628,7 @@ fn check_code(cx: &LateContext<'_>, text: &str, edition: Edition, span: Span) {
                 let mut parser = match maybe_new_parser_from_source_str(&sess, filename, code) {
                     Ok(p) => p,
                     Err(errs) => {
-                        for mut err in errs {
-                            err.cancel();
-                        }
+                        drop(errs);
                         return false;
                     },
                 };
@@ -668,7 +666,7 @@ fn check_code(cx: &LateContext<'_>, text: &str, edition: Edition, span: Span) {
                             _ => {},
                         },
                         Ok(None) => break,
-                        Err(mut e) => {
+                        Err(e) => {
                             e.cancel();
                             return false;
                         },
diff --git a/clippy_lints/src/write.rs b/clippy_lints/src/write.rs
index 1fa6301ebd7..a328ddda5ae 100644
--- a/clippy_lints/src/write.rs
+++ b/clippy_lints/src/write.rs
@@ -534,7 +534,7 @@ impl Write {
             match parser
                 .parse_expr()
                 .map(rustc_ast::ptr::P::into_inner)
-                .map_err(|mut e| e.cancel())
+                .map_err(|e| e.cancel())
             {
                 // write!(e, ...)
                 Ok(p) if parser.eat(&token::Comma) => Some(p),
@@ -563,7 +563,7 @@ impl Write {
             }
 
             let comma_span = parser.prev_token.span;
-            let token_expr = if let Ok(expr) = parser.parse_expr().map_err(|mut err| err.cancel()) {
+            let token_expr = if let Ok(expr) = parser.parse_expr().map_err(|err| err.cancel()) {
                 expr
             } else {
                 return (Some(fmtstr), None);