diff --git a/tokio-sync/benches/mpsc.rs b/tokio-sync/benches/mpsc.rs
index d83ae475c..bb351d3e5 100644
--- a/tokio-sync/benches/mpsc.rs
+++ b/tokio-sync/benches/mpsc.rs
@@ -1,4 +1,5 @@
 #![feature(test)]
+#![cfg_attr(test, deny(warnings))]
 
 extern crate tokio_sync;
 extern crate futures;
@@ -51,7 +52,7 @@ mod tokio {
 
     #[bench]
     fn bounded_tx_poll_ready(b: &mut Bencher) {
-        let (mut tx, rx) = channel::<i32>(1);
+        let (mut tx, _rx) = channel::<i32>(1);
         b.iter(|| {
             future::lazy(|| {
                 assert!(tx.poll_ready().unwrap().is_ready());
@@ -63,7 +64,7 @@ mod tokio {
 
     #[bench]
     fn bounded_tx_poll_not_ready(b: &mut Bencher) {
-        let (mut tx, rx) = channel::<i32>(1);
+        let (mut tx, _rx) = channel::<i32>(1);
         tx.try_send(1).unwrap();
         b.iter(|| {
             future::lazy(|| {
@@ -163,7 +164,7 @@ mod tokio {
                 .take(4 * 1_000);
 
             for v in rx {
-                test::black_box(v);
+                let _ = test::black_box(v);
             }
         });
 
@@ -209,7 +210,7 @@ mod tokio {
                 .take(THREADS * ITERS);
 
             for v in rx {
-                test::black_box(v);
+                let _ = test::black_box(v);
             }
         });
 
@@ -268,7 +269,7 @@ mod legacy {
 
     #[bench]
     fn bounded_tx_poll_ready(b: &mut Bencher) {
-        let (mut tx, rx) = channel::<i32>(0);
+        let (mut tx, _rx) = channel::<i32>(0);
         b.iter(|| {
             future::lazy(|| {
                 assert!(tx.poll_ready().unwrap().is_ready());
@@ -280,7 +281,7 @@ mod legacy {
 
     #[bench]
     fn bounded_tx_poll_not_ready(b: &mut Bencher) {
-        let (mut tx, rx) = channel::<i32>(0);
+        let (mut tx, _rx) = channel::<i32>(0);
         tx.try_send(1).unwrap();
         b.iter(|| {
             future::lazy(|| {
@@ -379,7 +380,7 @@ mod legacy {
                 .take(4 * 1_000);
 
             for v in rx {
-                test::black_box(v);
+                let _ = test::black_box(v);
             }
         });
 
@@ -425,7 +426,7 @@ mod legacy {
                 .take(THREADS * ITERS);
 
             for v in rx {
-                test::black_box(v);
+                let _ = test::black_box(v);
             }
         });
 
diff --git a/tokio-sync/benches/oneshot.rs b/tokio-sync/benches/oneshot.rs
index 97dd1ee94..873eb1e80 100644
--- a/tokio-sync/benches/oneshot.rs
+++ b/tokio-sync/benches/oneshot.rs
@@ -1,4 +1,5 @@
 #![feature(test)]
+#![cfg_attr(test, deny(warnings))]
 
 extern crate tokio_sync;
 extern crate futures;
diff --git a/tokio-sync/tests/atomic_task.rs b/tokio-sync/tests/atomic_task.rs
index d630e3ea9..cfe91e1af 100644
--- a/tokio-sync/tests/atomic_task.rs
+++ b/tokio-sync/tests/atomic_task.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 extern crate tokio_mock_task;
 extern crate tokio_sync;
diff --git a/tokio-sync/tests/fuzz_atomic_task.rs b/tokio-sync/tests/fuzz_atomic_task.rs
index 961d16df9..1ba1a7751 100644
--- a/tokio-sync/tests/fuzz_atomic_task.rs
+++ b/tokio-sync/tests/fuzz_atomic_task.rs
@@ -1,7 +1,10 @@
+#![deny(warnings)]
+
 extern crate futures;
 #[macro_use]
 extern crate loom;
 
+#[allow(dead_code)]
 #[path = "../src/task/atomic_task.rs"]
 mod atomic_task;
 
diff --git a/tokio-sync/tests/fuzz_list.rs b/tokio-sync/tests/fuzz_list.rs
index d0207ccb6..43799020e 100644
--- a/tokio-sync/tests/fuzz_list.rs
+++ b/tokio-sync/tests/fuzz_list.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 #[macro_use]
 extern crate loom;
diff --git a/tokio-sync/tests/fuzz_oneshot.rs b/tokio-sync/tests/fuzz_oneshot.rs
index 1b8cbe33a..2d3bda96a 100644
--- a/tokio-sync/tests/fuzz_oneshot.rs
+++ b/tokio-sync/tests/fuzz_oneshot.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 extern crate loom;
 
diff --git a/tokio-sync/tests/fuzz_semaphore.rs b/tokio-sync/tests/fuzz_semaphore.rs
index 9bd88467f..aa0480974 100644
--- a/tokio-sync/tests/fuzz_semaphore.rs
+++ b/tokio-sync/tests/fuzz_semaphore.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 #[macro_use]
 extern crate futures;
 #[macro_use]
diff --git a/tokio-sync/tests/mpsc.rs b/tokio-sync/tests/mpsc.rs
index 5083e4ccf..f58305e0b 100644
--- a/tokio-sync/tests/mpsc.rs
+++ b/tokio-sync/tests/mpsc.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 extern crate tokio_mock_task;
 extern crate tokio_sync;
diff --git a/tokio-sync/tests/oneshot.rs b/tokio-sync/tests/oneshot.rs
index 3919d8589..2413f909a 100644
--- a/tokio-sync/tests/oneshot.rs
+++ b/tokio-sync/tests/oneshot.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 extern crate tokio_mock_task;
 extern crate tokio_sync;
diff --git a/tokio-sync/tests/semaphore.rs b/tokio-sync/tests/semaphore.rs
index 74e98cbb3..2249045f2 100644
--- a/tokio-sync/tests/semaphore.rs
+++ b/tokio-sync/tests/semaphore.rs
@@ -1,3 +1,5 @@
+#![deny(warnings)]
+
 extern crate futures;
 extern crate tokio_mock_task;
 extern crate tokio_sync;