diff --git a/CHANGES.md b/CHANGES.md
index 0df4d27..f854d4a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,8 @@
+unreleased
+--------------
+- gluten-async: update async and core to v0.17.0
+  ([#78)(https://github.com/anmonteiro/gluten/pull/78))
+
 0.5.1 2024-06-04
 --------------
 
diff --git a/async/gluten_async.ml b/async/gluten_async.ml
index 4e388cb..7a84d3f 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 ivar n);
+      (fun n -> Ivar.fill_exn 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 read_complete ();
+          Ivar.fill_exn 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 write_complete ()
+      | `Close _ -> Ivar.fill_exn write_complete ()
     in
     let conn_monitor = Monitor.create () in
     Scheduler.within ~monitor:conn_monitor reader_thread;
diff --git a/dune-project b/dune-project
index b4ba9ee..0322b87 100644
--- a/dune-project
+++ b/dune-project
@@ -87,9 +87,9 @@
   (faraday-async
    (>= "0.7.3"))
   (async
-   (>= "v0.15.0"))
+   (>= "v0.17.0"))
   (core
-   (>= "v0.15.0")))
+   (>= "v0.17.0")))
  (depopts async_ssl tls-async))
 
 (package
diff --git a/gluten-async.opam b/gluten-async.opam
index 5fc2f46..f2a38dc 100644
--- a/gluten-async.opam
+++ b/gluten-async.opam
@@ -11,8 +11,8 @@ depends: [
   "ocaml" {>= "4.08.0"}
   "gluten" {= version}
   "faraday-async" {>= "0.7.3"}
-  "async" {>= "v0.15.0"}
-  "core" {>= "v0.15.0"}
+  "async" {>= "v0.17.0"}
+  "core" {>= "v0.17.0"}
   "odoc" {with-doc}
 ]
 depopts: ["async_ssl" "tls-async"]