diff --git a/src/js/async.mbt b/src/js/async.mbt
index 5daae28..a57301f 100644
--- a/src/js/async.mbt
+++ b/src/js/async.mbt
@@ -9,16 +9,6 @@ pub fn async_run(f : async () -> Unit) -> Unit = "%async.run"
 ///|
 pub extern type Promise
 
-///|
-pub typealias AsyncOp = () -> Promise
-
-///|
-extern "js" fn async_wrap_ffi(
-  op : AsyncOp,
-  on_ok : (Value) -> Unit,
-  on_err : (Value) -> Unit
-) -> Unit = "(op, on_ok, on_err) => op().then((t) => on_ok(t), (e) => on_err(e))"
-
 ///|
 extern "js" fn Promise::wait_ffi(
   self : Promise,
diff --git a/src/js/async_deprecated.mbt b/src/js/async_deprecated.mbt
index 1f6db45..2aff311 100644
--- a/src/js/async_deprecated.mbt
+++ b/src/js/async_deprecated.mbt
@@ -1,3 +1,13 @@
+///| @alert deprecated "use Promise directly instead"
+pub typealias AsyncOp = () -> Promise
+
+///|
+extern "js" fn async_wrap_ffi(
+  op : AsyncOp,
+  on_ok : (Value) -> Unit,
+  on_err : (Value) -> Unit
+) -> Unit = "(op, on_ok, on_err) => op().then((t) => on_ok(t), (e) => on_err(e))"
+
 ///| @alert deprecated "use Promise::wait instead"
 pub async fn async_wrap(op : AsyncOp) -> Value! {
   suspend!!(fn(k, ke) { async_wrap_ffi(op, k, fn(e) { ke(Error_(e)) }) })