diff --git a/tokio/src/sync/mutex.rs b/tokio/src/sync/mutex.rs
index 38ff1d7d5c8..6b51b405681 100644
--- a/tokio/src/sync/mutex.rs
+++ b/tokio/src/sync/mutex.rs
@@ -138,7 +138,7 @@ fn bounds() {
     fn check_send<T: Send>() {}
     fn check_unpin<T: Unpin>() {}
     // This has to take a value, since the async fn's return type is unnameable.
-    fn check_send_sync_val<T: Send + Sync>(t: T) {}
+    fn check_send_sync_val<T: Send + Sync>(_t: T) {}
     fn check_send_sync<T: Send + Sync>() {}
     check_send::<MutexGuard<'_, u32>>();
     check_unpin::<Mutex<u32>>();
diff --git a/tokio/src/sync/rwlock.rs b/tokio/src/sync/rwlock.rs
index 0a4ec472e52..0f7991a5bf8 100644
--- a/tokio/src/sync/rwlock.rs
+++ b/tokio/src/sync/rwlock.rs
@@ -134,7 +134,7 @@ fn bounds() {
     fn check_sync<T: Sync>() {}
     fn check_unpin<T: Unpin>() {}
     // This has to take a value, since the async fn's return type is unnameable.
-    fn check_send_sync_val<T: Send + Sync>(t: T) {}
+    fn check_send_sync_val<T: Send + Sync>(_t: T) {}
 
     check_send::<RwLock<u32>>();
     check_sync::<RwLock<u32>>();
diff --git a/tokio/src/sync/semaphore.rs b/tokio/src/sync/semaphore.rs
index e58db987e99..4cce7e8f5bc 100644
--- a/tokio/src/sync/semaphore.rs
+++ b/tokio/src/sync/semaphore.rs
@@ -40,7 +40,7 @@ pub struct TryAcquireError(());
 fn bounds() {
     fn check_unpin<T: Unpin>() {}
     // This has to take a value, since the async fn's return type is unnameable.
-    fn check_send_sync_val<T: Send + Sync>(t: T) {}
+    fn check_send_sync_val<T: Send + Sync>(_t: T) {}
     fn check_send_sync<T: Send + Sync>() {}
     check_unpin::<Semaphore>();
     check_unpin::<SemaphorePermit<'_>>();