diff --git a/rayon-core/src/job.rs b/rayon-core/src/job.rs
index ac1c6aaf6..cd205990d 100644
--- a/rayon-core/src/job.rs
+++ b/rayon-core/src/job.rs
@@ -8,7 +8,7 @@ use unwind;
 pub(super) enum JobResult<T> {
     None,
     Ok(T),
-    Panic(Box<Any + Send>),
+    Panic(Box<dyn Any + Send>),
 }
 
 /// A `Job` is used to advertise work for other threads that they may
diff --git a/rayon-core/src/join/mod.rs b/rayon-core/src/join/mod.rs
index 04d70c095..676fbdfbf 100644
--- a/rayon-core/src/join/mod.rs
+++ b/rayon-core/src/join/mod.rs
@@ -194,7 +194,7 @@ where
 unsafe fn join_recover_from_panic(
     worker_thread: &WorkerThread,
     job_b_latch: &SpinLatch,
-    err: Box<Any + Send>,
+    err: Box<dyn Any + Send>,
 ) -> ! {
     worker_thread.wait_until(job_b_latch);
     unwind::resume_unwinding(err)
diff --git a/rayon-core/src/lib.rs b/rayon-core/src/lib.rs
index 5f8d0e971..de87ed523 100644
--- a/rayon-core/src/lib.rs
+++ b/rayon-core/src/lib.rs
@@ -140,7 +140,7 @@ pub struct ThreadPoolBuilder<S = DefaultSpawn> {
     panic_handler: Option<Box<PanicHandler>>,
 
     /// Closure to compute the name of a thread.
-    get_thread_name: Option<Box<FnMut(usize) -> String>>,
+    get_thread_name: Option<Box<dyn FnMut(usize) -> String>>,
 
     /// The stack size for the created worker threads
     stack_size: Option<usize>,
@@ -170,17 +170,17 @@ pub struct Configuration {
 
 /// The type for a panic handling closure. Note that this same closure
 /// may be invoked multiple times in parallel.
-type PanicHandler = Fn(Box<Any + Send>) + Send + Sync;
+type PanicHandler = dyn Fn(Box<dyn Any + Send>) + Send + Sync;
 
 /// The type for a closure that gets invoked when a thread starts. The
 /// closure is passed the index of the thread on which it is invoked.
 /// Note that this same closure may be invoked multiple times in parallel.
-type StartHandler = Fn(usize) + Send + Sync;
+type StartHandler = dyn Fn(usize) + Send + Sync;
 
 /// The type for a closure that gets invoked when a thread exits. The
 /// closure is passed the index of the thread on which is is invoked.
 /// Note that this same closure may be invoked multiple times in parallel.
-type ExitHandler = Fn(usize) + Send + Sync;
+type ExitHandler = dyn Fn(usize) + Send + Sync;
 
 // NB: We can't `#[derive(Default)]` because `S` is left ambiguous.
 impl Default for ThreadPoolBuilder {
@@ -481,7 +481,7 @@ impl<S> ThreadPoolBuilder<S> {
     /// in a call to `std::panic::catch_unwind()`.
     pub fn panic_handler<H>(mut self, panic_handler: H) -> Self
     where
-        H: Fn(Box<Any + Send>) + Send + Sync + 'static,
+        H: Fn(Box<dyn Any + Send>) + Send + Sync + 'static,
     {
         self.panic_handler = Some(Box::new(panic_handler));
         self
@@ -585,7 +585,7 @@ impl Configuration {
     }
 
     /// Deprecated in favor of `ThreadPoolBuilder::build`.
-    pub fn build(self) -> Result<ThreadPool, Box<Error + 'static>> {
+    pub fn build(self) -> Result<ThreadPool, Box<dyn Error + 'static>> {
         self.builder.build().map_err(Box::from)
     }
 
@@ -607,7 +607,7 @@ impl Configuration {
     /// Deprecated in favor of `ThreadPoolBuilder::panic_handler`.
     pub fn panic_handler<H>(mut self, panic_handler: H) -> Configuration
     where
-        H: Fn(Box<Any + Send>) + Send + Sync + 'static,
+        H: Fn(Box<dyn Any + Send>) + Send + Sync + 'static,
     {
         self.builder = self.builder.panic_handler(panic_handler);
         self
@@ -678,7 +678,7 @@ impl fmt::Display for ThreadPoolBuildError {
 /// Deprecated in favor of `ThreadPoolBuilder::build_global`.
 #[deprecated(note = "use `ThreadPoolBuilder::build_global`")]
 #[allow(deprecated)]
-pub fn initialize(config: Configuration) -> Result<(), Box<Error>> {
+pub fn initialize(config: Configuration) -> Result<(), Box<dyn Error>> {
     config.into_builder().build_global().map_err(Box::from)
 }
 
diff --git a/rayon-core/src/registry.rs b/rayon-core/src/registry.rs
index 372fcf3b8..1c43ac8d8 100644
--- a/rayon-core/src/registry.rs
+++ b/rayon-core/src/registry.rs
@@ -19,7 +19,7 @@ use std::ptr;
 #[allow(deprecated)]
 use std::sync::atomic::ATOMIC_USIZE_INIT;
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::{Arc, Once, ONCE_INIT};
+use std::sync::{Arc, Once};
 use std::thread;
 use std::usize;
 use unwind;
@@ -161,7 +161,7 @@ pub(super) struct Registry {
 /// Initialization
 
 static mut THE_REGISTRY: Option<&'static Arc<Registry>> = None;
-static THE_REGISTRY_SET: Once = ONCE_INIT;
+static THE_REGISTRY_SET: Once = Once::new();
 
 /// Starts the worker threads (if that has not already happened). If
 /// initialization has not already occurred, use the default
@@ -322,7 +322,7 @@ impl Registry {
         self.thread_infos.len()
     }
 
-    pub(super) fn handle_panic(&self, err: Box<Any + Send>) {
+    pub(super) fn handle_panic(&self, err: Box<dyn Any + Send>) {
         match self.panic_handler {
             Some(ref handler) => {
                 // If the customizable panic handler itself panics,
diff --git a/rayon-core/src/scope/mod.rs b/rayon-core/src/scope/mod.rs
index a797beae0..c3ad5b259 100644
--- a/rayon-core/src/scope/mod.rs
+++ b/rayon-core/src/scope/mod.rs
@@ -50,7 +50,7 @@ struct ScopeBase<'scope> {
 
     /// if some job panicked, the error is stored here; it will be
     /// propagated to the one who created the scope
-    panic: AtomicPtr<Box<Any + Send + 'static>>,
+    panic: AtomicPtr<Box<dyn Any + Send + 'static>>,
 
     /// latch to set when the counter drops to zero (and hence this scope is complete)
     job_completed_latch: CountLatch,
@@ -59,7 +59,7 @@ struct ScopeBase<'scope> {
     /// all of which outlive `'scope`.  They're not actually required to be
     /// `Sync`, but it's still safe to let the `Scope` implement `Sync` because
     /// the closures are only *moved* across threads to be executed.
-    marker: PhantomData<Box<FnOnce(&Scope<'scope>) + Send + Sync + 'scope>>,
+    marker: PhantomData<Box<dyn FnOnce(&Scope<'scope>) + Send + Sync + 'scope>>,
 }
 
 /// Create a "fork-join" scope `s` and invokes the closure with a
@@ -572,7 +572,7 @@ impl<'scope> ScopeBase<'scope> {
         }
     }
 
-    unsafe fn job_panicked(&self, err: Box<Any + Send + 'static>) {
+    unsafe fn job_panicked(&self, err: Box<dyn Any + Send + 'static>) {
         // capture the first error we see, free the rest
         let nil = ptr::null_mut();
         let mut err = Box::new(err); // box up the fat ptr
@@ -613,7 +613,7 @@ impl<'scope> ScopeBase<'scope> {
             log!(ScopeCompletePanicked {
                 owner_thread: owner_thread.index()
             });
-            let value: Box<Box<Any + Send + 'static>> = mem::transmute(panic);
+            let value: Box<Box<dyn Any + Send + 'static>> = mem::transmute(panic);
             unwind::resume_unwinding(*value);
         } else {
             log!(ScopeCompleteNoPanic {
diff --git a/rayon-core/src/spawn/test.rs b/rayon-core/src/spawn/test.rs
index 59a9496b8..9b9daab17 100644
--- a/rayon-core/src/spawn/test.rs
+++ b/rayon-core/src/spawn/test.rs
@@ -27,7 +27,7 @@ fn panic_fwd() {
     let (tx, rx) = channel();
 
     let tx = Mutex::new(tx);
-    let panic_handler = move |err: Box<Any + Send>| {
+    let panic_handler = move |err: Box<dyn Any + Send>| {
         let tx = tx.lock().unwrap();
         if let Some(&msg) = err.downcast_ref::<&str>() {
             if msg == "Hello, world!" {
@@ -87,7 +87,7 @@ fn custom_panic_handler_and_spawn() {
     // channel; since the closure is potentially executed in parallel
     // with itself, we have to wrap `tx` in a mutex.
     let tx = Mutex::new(tx);
-    let panic_handler = move |e: Box<Any + Send>| {
+    let panic_handler = move |e: Box<dyn Any + Send>| {
         tx.lock().unwrap().send(e).unwrap();
     };
 
diff --git a/rayon-core/src/thread_pool/mod.rs b/rayon-core/src/thread_pool/mod.rs
index 8a1875343..093546ee0 100644
--- a/rayon-core/src/thread_pool/mod.rs
+++ b/rayon-core/src/thread_pool/mod.rs
@@ -57,7 +57,7 @@ impl ThreadPool {
     #[deprecated(note = "Use `ThreadPoolBuilder::build`")]
     #[allow(deprecated)]
     /// Deprecated in favor of `ThreadPoolBuilder::build`.
-    pub fn new(configuration: Configuration) -> Result<ThreadPool, Box<Error>> {
+    pub fn new(configuration: Configuration) -> Result<ThreadPool, Box<dyn Error>> {
         Self::build(configuration.into_builder()).map_err(Box::from)
     }
 
diff --git a/rayon-core/src/unwind.rs b/rayon-core/src/unwind.rs
index fceed410b..9671fa578 100644
--- a/rayon-core/src/unwind.rs
+++ b/rayon-core/src/unwind.rs
@@ -17,7 +17,7 @@ where
     panic::catch_unwind(AssertUnwindSafe(func))
 }
 
-pub(super) fn resume_unwinding(payload: Box<Any + Send>) -> ! {
+pub(super) fn resume_unwinding(payload: Box<dyn Any + Send>) -> ! {
     panic::resume_unwind(payload)
 }
 
diff --git a/rayon-demo/src/tsp/mod.rs b/rayon-demo/src/tsp/mod.rs
index d29bdc087..dcb0d2c66 100644
--- a/rayon-demo/src/tsp/mod.rs
+++ b/rayon-demo/src/tsp/mod.rs
@@ -103,7 +103,7 @@ fn run_solver(datafile: &Path, seq_threshold: usize, from: usize) -> Result<(),
     Ok(())
 }
 
-fn parse_solver(datafile: &Path) -> Result<Graph, Box<Error>> {
+fn parse_solver(datafile: &Path) -> Result<Graph, Box<dyn Error>> {
     let mut file = File::open(datafile)?;
     let mut text = String::new();
     file.read_to_string(&mut text)?;
diff --git a/src/iter/collect/mod.rs b/src/iter/collect/mod.rs
index cab25e86d..21328108b 100644
--- a/src/iter/collect/mod.rs
+++ b/src/iter/collect/mod.rs
@@ -139,8 +139,8 @@ where
                 // This works like `extend`, but `Vec::append` is more efficient.
                 let list = super::extend::collect(par_iter);
                 self.reserve(super::extend::len(&list));
-                for ref mut vec in list {
-                    self.append(vec);
+                for mut vec in list {
+                    self.append(&mut vec);
                 }
             }
         }
diff --git a/src/iter/extend.rs b/src/iter/extend.rs
index 82221e1ae..9de3ebff3 100644
--- a/src/iter/extend.rs
+++ b/src/iter/extend.rs
@@ -43,8 +43,8 @@ fn as_list<T>(item: T) -> LinkedList<T> {
     list
 }
 
-fn list_append<T>(mut list1: LinkedList<T>, ref mut list2: LinkedList<T>) -> LinkedList<T> {
-    list1.append(list2);
+fn list_append<T>(mut list1: LinkedList<T>, mut list2: LinkedList<T>) -> LinkedList<T> {
+    list1.append(&mut list2);
     list1
 }
 
diff --git a/src/iter/test.rs b/src/iter/test.rs
index d2a6c1dee..b632383f3 100644
--- a/src/iter/test.rs
+++ b/src/iter/test.rs
@@ -985,7 +985,7 @@ fn check_chunks() {
 
     let par_sum_product_triples: i32 = a.par_chunks(3).map(|c| c.iter().product::<i32>()).sum();
     let seq_sum_product_triples = a.chunks(3).map(|c| c.iter().product::<i32>()).sum();
-    assert_eq!(par_sum_product_triples, 5_0 + 12_00 + 2_000_0000 + 1);
+    assert_eq!(par_sum_product_triples, 5_0 + 12_00 + 20_000_000 + 1);
     assert_eq!(par_sum_product_triples, seq_sum_product_triples);
 }