diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/UnityAsyncExtensions.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/UnityAsyncExtensions.cs
index 8f8e3a1..2f72604 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/UnityAsyncExtensions.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/UnityAsyncExtensions.cs
@@ -15,11 +15,15 @@ namespace Cysharp.Threading.Tasks
     {
         #region AsyncOperation
 
+#if !UNITY_2023_1_OR_NEWER
+        // from Unity2023.1.0a15, AsyncOperationAwaitableExtensions.GetAwaiter is defined in UnityEngine.
+
         public static AsyncOperationAwaiter GetAwaiter(this AsyncOperation asyncOperation)
         {
             Error.ThrowArgumentNullException(asyncOperation, nameof(asyncOperation));
             return new AsyncOperationAwaiter(asyncOperation);
         }
+#endif
 
         public static UniTask WithCancellation(this AsyncOperation asyncOperation, CancellationToken cancellationToken)
         {