diff --git a/CHANGES.md b/CHANGES.md
index f854d4a..d82990c 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,6 @@
 unreleased
 --------------
-- gluten-async: update async and core to v0.17.0
+- gluten-async: Silence async deprecation warnings
   ([#78)(https://github.com/anmonteiro/gluten/pull/78))
 
 0.5.1 2024-06-04
diff --git a/async/dune b/async/dune
index 280c42e..90bbc27 100644
--- a/async/dune
+++ b/async/dune
@@ -18,4 +18,5 @@
    from
    (tls-async -> tls_io.real.ml)
    (!tls-async -> tls_io.dummy.ml)))
- (modules gluten_async gluten_async_intf ssl_io tls_io))
+ (modules gluten_async gluten_async_intf ssl_io tls_io)
+ (flags (:standard -w -3)))
diff --git a/async/gluten_async.ml b/async/gluten_async.ml
index 7a84d3f..4e388cb 100644
--- a/async/gluten_async.ml
+++ b/async/gluten_async.ml
@@ -44,7 +44,7 @@ module Make_IO_Loop (Io : Gluten_async_intf.IO) = struct
     Buffer.put
       ~f:(fun buf ~off ~len k -> Async.upon (Io.read socket buf ~off ~len) k)
       read_buffer
-      (fun n -> Ivar.fill_exn ivar n);
+      (fun n -> Ivar.fill ivar n);
     Ivar.read ivar
 
   let start :
@@ -76,7 +76,7 @@ module Make_IO_Loop (Io : Gluten_async_intf.IO) = struct
           Runtime.yield_reader t reader_thread;
           Deferred.return ()
         | `Close ->
-          Ivar.fill_exn read_complete ();
+          Ivar.fill read_complete ();
           Io.shutdown_receive socket;
           Deferred.return ()
       in
@@ -91,7 +91,7 @@ module Make_IO_Loop (Io : Gluten_async_intf.IO) = struct
         Runtime.report_write_result t result;
         writer_thread ()
       | `Yield -> Runtime.yield_writer t writer_thread
-      | `Close _ -> Ivar.fill_exn write_complete ()
+      | `Close _ -> Ivar.fill write_complete ()
     in
     let conn_monitor = Monitor.create () in
     Scheduler.within ~monitor:conn_monitor reader_thread;