diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
index 7d872b1a66b..462bcd15fa9 100644
--- a/library/alloc/src/alloc.rs
+++ b/library/alloc/src/alloc.rs
@@ -213,12 +213,12 @@ unsafe impl AllocRef for Global {
     }
 
     #[inline]
-    fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
+    fn alloc_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         self.alloc_impl(layout, true)
     }
 
     #[inline]
-    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+    unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout) {
         if layout.size() != 0 {
             // SAFETY: `layout` is non-zero in size,
             // other conditions must be upheld by the caller
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index 62675665f03..5b4a4957f6c 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -169,7 +169,7 @@ impl<T, A: AllocRef> RawVec<T, A> {
         Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
     }
 
-    fn allocate_in(capacity: usize, init: AllocInit, mut alloc: A) -> Self {
+    fn allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Self {
         if mem::size_of::<T>() == 0 {
             Self::new_in(alloc)
         } else {
diff --git a/library/alloc/src/raw_vec/tests.rs b/library/alloc/src/raw_vec/tests.rs
index 2ed9d3685c6..e4c8b3709df 100644
--- a/library/alloc/src/raw_vec/tests.rs
+++ b/library/alloc/src/raw_vec/tests.rs
@@ -34,7 +34,7 @@ fn allocator_param() {
                 err @ Err(_) => err,
             }
         }
-        unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+        unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout) {
             unsafe { Global.dealloc(ptr, layout) }
         }
     }
diff --git a/library/alloc/tests/heap.rs b/library/alloc/tests/heap.rs
index cbde2a7e28e..a7239a4b14f 100644
--- a/library/alloc/tests/heap.rs
+++ b/library/alloc/tests/heap.rs
@@ -11,7 +11,7 @@ fn std_heap_overaligned_request() {
     check_overalign_requests(Global)
 }
 
-fn check_overalign_requests<T: AllocRef>(mut allocator: T) {
+fn check_overalign_requests<T: AllocRef>(allocator: T) {
     for &align in &[4, 8, 16, 32] {
         // less than and bigger than `MIN_ALIGN`
         for &size in &[align / 2, align - 1] {
diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs
index b7dd249d093..5f9092fe703 100644
--- a/library/core/src/alloc/mod.rs
+++ b/library/core/src/alloc/mod.rs
@@ -126,7 +126,7 @@ pub unsafe trait AllocRef {
     /// call the [`handle_alloc_error`] function, rather than directly invoking `panic!` or similar.
     ///
     /// [`handle_alloc_error`]: ../../alloc/alloc/fn.handle_alloc_error.html
-    fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
+    fn alloc_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         let ptr = self.alloc(layout)?;
         // SAFETY: `alloc` returns a valid memory block
         unsafe { ptr.as_non_null_ptr().as_ptr().write_bytes(0, ptr.len()) }
@@ -142,7 +142,7 @@ pub unsafe trait AllocRef {
     ///
     /// [*currently allocated*]: #currently-allocated-memory
     /// [*fit*]: #memory-fitting
-    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout);
+    unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout);
 
     /// Attempts to extend the memory block.
     ///
@@ -353,12 +353,12 @@ where
     }
 
     #[inline]
-    fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
+    fn alloc_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         (**self).alloc_zeroed(layout)
     }
 
     #[inline]
-    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+    unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout) {
         // SAFETY: the safety contract must be upheld by the caller
         unsafe { (**self).dealloc(ptr, layout) }
     }
diff --git a/library/std/src/alloc.rs b/library/std/src/alloc.rs
index 86ae4cf4dd2..f41aa28b5ec 100644
--- a/library/std/src/alloc.rs
+++ b/library/std/src/alloc.rs
@@ -207,12 +207,12 @@ unsafe impl AllocRef for System {
     }
 
     #[inline]
-    fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
+    fn alloc_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocErr> {
         self.alloc_impl(layout, true)
     }
 
     #[inline]
-    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+    unsafe fn dealloc(&self, ptr: NonNull<u8>, layout: Layout) {
         if layout.size() != 0 {
             // SAFETY: `layout` is non-zero in size,
             // other conditions must be upheld by the caller