diff --git a/compiler/rustc_ast_pretty/src/pp.rs b/compiler/rustc_ast_pretty/src/pp.rs
index c93022308a37d..7ab8c3eaba227 100644
--- a/compiler/rustc_ast_pretty/src/pp.rs
+++ b/compiler/rustc_ast_pretty/src/pp.rs
@@ -360,7 +360,7 @@ impl Printer {
 
     fn check_stack(&mut self, mut depth: usize) {
         while let Some(&index) = self.scan_stack.back() {
-            let mut entry = &mut self.buf[index];
+            let entry = &mut self.buf[index];
             match entry.token {
                 Token::Begin(_) => {
                     if depth == 0 {
diff --git a/compiler/rustc_borrowck/src/member_constraints.rs b/compiler/rustc_borrowck/src/member_constraints.rs
index db5b8f464c852..842e90080582f 100644
--- a/compiler/rustc_borrowck/src/member_constraints.rs
+++ b/compiler/rustc_borrowck/src/member_constraints.rs
@@ -221,7 +221,7 @@ fn append_list(
 ) {
     let mut p = target_list;
     loop {
-        let mut r = &mut constraints[p];
+        let r = &mut constraints[p];
         match r.next_constraint {
             Some(q) => p = q,
             None => {
diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs
index 421b3df2d533e..6ab5556e951d9 100644
--- a/compiler/rustc_hir_analysis/src/check/region.rs
+++ b/compiler/rustc_hir_analysis/src/check/region.rs
@@ -421,7 +421,7 @@ fn resolve_expr<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, expr: &'tcx h
             let target_scopes = visitor.fixup_scopes.drain(start_point..);
 
             for scope in target_scopes {
-                let mut yield_data =
+                let yield_data =
                     visitor.scope_tree.yield_in_scope.get_mut(&scope).unwrap().last_mut().unwrap();
                 let count = yield_data.expr_and_pat_count;
                 let span = yield_data.span;
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index d9f03fe14072e..775fad1a365c2 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -917,7 +917,7 @@ mod parse {
             }
         }
 
-        let mut options = slot.get_or_insert_default();
+        let options = slot.get_or_insert_default();
         let mut seen_always = false;
         let mut seen_never = false;
         let mut seen_ignore_loops = false;
diff --git a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.fixed b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.fixed
index b69bad98888e3..556c95438817e 100644
--- a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.fixed
+++ b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.fixed
@@ -11,7 +11,7 @@ fn main() {
     let mut map = HashMap::new();
     map.insert("a", Test { v: 0 });
 
-    for (_k, mut v) in map.iter_mut() {
+    for (_k, v) in map.iter_mut() {
         //~^ HELP use mutable method
         //~| NOTE this iterator yields `&` references
         v.v += 1;
diff --git a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.rs b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.rs
index 9284410dfa383..b9d49a074eade 100644
--- a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.rs
+++ b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.rs
@@ -11,7 +11,7 @@ fn main() {
     let mut map = HashMap::new();
     map.insert("a", Test { v: 0 });
 
-    for (_k, mut v) in map.iter() {
+    for (_k, v) in map.iter() {
         //~^ HELP use mutable method
         //~| NOTE this iterator yields `&` references
         v.v += 1;
diff --git a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.stderr b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.stderr
index 74433daa6acf2..c442ed6377a8c 100644
--- a/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.stderr
+++ b/tests/ui/suggestions/suggest-mut-method-for-loop-hashmap.stderr
@@ -1,11 +1,11 @@
 error[E0594]: cannot assign to `v.v`, which is behind a `&` reference
   --> $DIR/suggest-mut-method-for-loop-hashmap.rs:17:9
    |
-LL |     for (_k, mut v) in map.iter() {
-   |                        ----------
-   |                        |   |
-   |                        |   help: use mutable method: `iter_mut()`
-   |                        this iterator yields `&` references
+LL |     for (_k, v) in map.iter() {
+   |                    ----------
+   |                    |   |
+   |                    |   help: use mutable method: `iter_mut()`
+   |                    this iterator yields `&` references
 ...
 LL |         v.v += 1;
    |         ^^^^^^^^ `v` is a `&` reference, so the data it refers to cannot be written