diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/AsyncUnit.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/AsyncUnit.cs
index 7a6091e..1d4bc74 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/AsyncUnit.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/AsyncUnit.cs
@@ -4,7 +4,7 @@ using System;
 
 namespace Cysharp.Threading.Tasks
 {
-    public struct AsyncUnit : IEquatable<AsyncUnit>
+    public readonly struct AsyncUnit : IEquatable<AsyncUnit>
     {
         public static readonly AsyncUnit Default = new AsyncUnit();
 
diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTaskVoid.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTaskVoid.cs
index 3f593b0..10711a5 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTaskVoid.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/UniTaskVoid.cs
@@ -9,41 +9,41 @@ using Cysharp.Threading.Tasks.CompilerServices;
 namespace Cysharp.Threading.Tasks
 {
     [AsyncMethodBuilder(typeof(AsyncUniTaskVoidMethodBuilder))]
-    public struct UniTaskVoid
+    public readonly struct UniTaskVoid
     {
         public void Forget()
         {
         }
 
-        [DebuggerHidden]
-        public Awaiter GetAwaiter()
-        {
-            return new Awaiter();
-        }
+        //        [DebuggerHidden]
+        //        public Awaiter GetAwaiter()
+        //        {
+        //            return new Awaiter();
+        //        }
 
-        public struct Awaiter : ICriticalNotifyCompletion
-        {
-            [DebuggerHidden]
-            public bool IsCompleted => true;
+        //        public struct Awaiter : ICriticalNotifyCompletion
+        //        {
+        //            [DebuggerHidden]
+        //            public bool IsCompleted => true;
 
-            [DebuggerHidden]
-            public void GetResult()
-            {
-#if UNITY_2018_3_OR_NEWER
-                UnityEngine.Debug.LogWarning("UniTaskVoid can't await, always fire-and-forget. use Forget instead of await.");
-#endif
-            }
+        //            [DebuggerHidden]
+        //            public void GetResult()
+        //            {
+        //#if UNITY_2018_3_OR_NEWER
+        //                UnityEngine.Debug.LogWarning("UniTaskVoid can't await, always fire-and-forget. use Forget instead of await.");
+        //#endif
+        //            }
 
-            [DebuggerHidden]
-            public void OnCompleted(Action continuation)
-            {
-            }
+        //            [DebuggerHidden]
+        //            public void OnCompleted(Action continuation)
+        //            {
+        //            }
 
-            [DebuggerHidden]
-            public void UnsafeOnCompleted(Action continuation)
-            {
-            }
-        }
+        //            [DebuggerHidden]
+        //            public void UnsafeOnCompleted(Action continuation)
+        //            {
+        //            }
+        //        }
     }
 }