diff --git a/src/cond_var/cond_var.mbt b/src/cond_var/cond_var.mbt
index 4de58309..c3d09b19 100644
--- a/src/cond_var/cond_var.mbt
+++ b/src/cond_var/cond_var.mbt
@@ -30,6 +30,7 @@ priv struct Waiter {
 
 ///|
 /// A condition variable that can be used for synchronization between tasks.
+#valtype
 struct Cond {
   waiters : @deque.Deque[Waiter]
 }
diff --git a/src/internal/coroutine/coroutine.mbt b/src/internal/coroutine/coroutine.mbt
index 64f9832a..33994480 100644
--- a/src/internal/coroutine/coroutine.mbt
+++ b/src/internal/coroutine/coroutine.mbt
@@ -13,7 +13,7 @@
 // limitations under the License.
 
 ///|
-priv enum State {
+enum State {
   Done
   Fail(Error)
   Running
@@ -21,7 +21,7 @@ priv enum State {
 }
 
 ///|
-struct Coroutine {
+pub struct Coroutine {
   coro_id : Int
   mut state : State
   mut shielded : Bool
diff --git a/src/internal/coroutine/pkg.generated.mbti b/src/internal/coroutine/pkg.generated.mbti
index 5b50dcd2..2aa8e2a6 100644
--- a/src/internal/coroutine/pkg.generated.mbti
+++ b/src/internal/coroutine/pkg.generated.mbti
@@ -3,6 +3,7 @@ package "moonbitlang/async/internal/coroutine"
 
 import {
   "moonbitlang/core/debug",
+  "moonbitlang/core/set",
 }
 
 // Values
@@ -32,7 +33,14 @@ pub(all) suberror Cancelled derive(@debug.Debug)
 pub impl Show for Cancelled
 
 // Types and methods
-type Coroutine
+pub struct Coroutine {
+  coro_id : Int
+  mut state : State
+  mut shielded : Bool
+  mut cancelled : Bool
+  mut ready : Bool
+  downstream : @set.Set[Coroutine]
+}
 pub fn Coroutine::cancel(Self) -> Unit
 pub fn Coroutine::check_error(Self) -> Unit raise
 pub fn Coroutine::unwrap(Self) -> Unit raise
@@ -41,6 +49,8 @@ pub fn Coroutine::wake(Self) -> Unit
 pub impl Eq for Coroutine
 pub impl Hash for Coroutine
 
+type State
+
 // Type aliases
 
 // Traits
diff --git a/src/task.mbt b/src/task.mbt
index c83282fb..48f90cc1 100644
--- a/src/task.mbt
+++ b/src/task.mbt
@@ -15,6 +15,7 @@
 ///|
 /// `Task[X]` represents a running task with result type `X`,
 /// it can be used to wait and retrieve the result value of the task.
+#valtype
 struct Task[X] {
   value : Ref[X?]
   coro : @coroutine.Coroutine