diff --git a/src/lib.rs b/src/lib.rs
index 555aa66671a2..d5d2db33fc52 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -535,7 +535,7 @@ fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
 // Formatting which depends on the AST.
 fn format_ast<F>(
     krate: &ast::Crate,
-    mut parse_session: &mut ParseSess,
+    parse_session: &mut ParseSess,
     main_file: &Path,
     config: &Config,
     codemap: &Rc<CodeMap>,
@@ -796,7 +796,7 @@ pub enum Input {
 }
 
 pub fn run(input: Input, config: &Config) -> Summary {
-    let mut out = &mut stdout();
+    let out = &mut stdout();
     output_header(out, config.write_mode()).ok();
     match format_input(input, config, Some(out)) {
         Ok((summary, _, report)) => {
diff --git a/src/macros.rs b/src/macros.rs
index 989aaaaa58c4..ae2a16510b8e 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -68,7 +68,7 @@ pub fn rewrite_macro(
     shape: Shape,
     position: MacroPosition,
 ) -> Option<String> {
-    let mut context = &mut context.clone();
+    let context = &mut context.clone();
     context.inside_macro = true;
     if context.config.use_try_shorthand() {
         if let Some(expr) = convert_try_mac(mac, context) {