diff --git a/tokio/src/sync/mpsc/chan.rs b/tokio/src/sync/mpsc/chan.rs
index 20e2c90d4..7f7f8b16d 100644
--- a/tokio/src/sync/mpsc/chan.rs
+++ b/tokio/src/sync/mpsc/chan.rs
@@ -306,13 +306,11 @@ impl<T, S: Semaphore> Rx<T, S> {
                             return Ready(Some(value));
                         }
                         Some(Read::Closed) => {
-                            // TODO: This check may not be required as it most
-                            // likely can only return `true` at this point. A
-                            // channel is closed when all tx handles are
+                            // A channel is closed when all tx handles are
                             // dropped. Dropping a tx handle releases memory,
                             // which ensures that if dropping the tx handle is
                             // visible, then all messages sent are also visible.
-                            assert!(self.inner.semaphore.is_idle());
+                            debug_assert!(self.inner.semaphore.is_idle());
                             coop.made_progress();
                             return Ready(None);
                         }
@@ -380,13 +378,11 @@ impl<T, S: Semaphore> Rx<T, S> {
                                 if number_added > 0 {
                                     self.inner.semaphore.add_permits(number_added);
                                 }
-                                // TODO: This check may not be required as it most
-                                // likely can only return `true` at this point. A
-                                // channel is closed when all tx handles are
+                                // A channel is closed when all tx handles are
                                 // dropped. Dropping a tx handle releases memory,
                                 // which ensures that if dropping the tx handle is
                                 // visible, then all messages sent are also visible.
-                                assert!(self.inner.semaphore.is_idle());
+                                debug_assert!(self.inner.semaphore.is_idle());
                                 coop.made_progress();
                                 return Ready(number_added);
                             }
@@ -415,7 +411,7 @@ impl<T, S: Semaphore> Rx<T, S> {
             try_recv!();
 
             if rx_fields.rx_closed && self.inner.semaphore.is_idle() {
-                assert!(buffer.is_empty());
+                debug_assert_eq!(buffer.len(), initial_length);
                 coop.made_progress();
                 Ready(0usize)
             } else {
diff --git a/tokio/tests/sync_mpsc.rs b/tokio/tests/sync_mpsc.rs
index 3ebac7390..048b94eb5 100644
--- a/tokio/tests/sync_mpsc.rs
+++ b/tokio/tests/sync_mpsc.rs
@@ -358,6 +358,30 @@ async fn send_recv_many_unbounded_capacity() {
     assert_eq!(expected, buffer);
 }
 
+#[maybe_tokio_test]
+async fn recv_many_with_non_empty_buffer_bounded_rx_closed_and_idle() {
+    let (_tx, mut rx) = mpsc::channel::<i32>(1);
+
+    let mut buffer: Vec<i32> = vec![1];
+
+    rx.close();
+
+    assert_eq!(0, rx.recv_many(&mut buffer, 1).await);
+    assert_eq!(vec![1], buffer);
+}
+
+#[maybe_tokio_test]
+async fn recv_many_with_non_empty_buffer_unbounded_rx_closed_and_idle() {
+    let (_tx, mut rx) = mpsc::unbounded_channel::<i32>();
+
+    let mut buffer: Vec<i32> = vec![1];
+
+    rx.close();
+
+    assert_eq!(0, rx.recv_many(&mut buffer, 1).await);
+    assert_eq!(vec![1], buffer);
+}
+
 #[tokio::test]
 #[cfg(feature = "full")]
 async fn async_send_recv_unbounded() {