diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/EnumeratorAsyncExtensions.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/EnumeratorAsyncExtensions.cs
index 4722b47..c2e4c51 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/EnumeratorAsyncExtensions.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/EnumeratorAsyncExtensions.cs
@@ -163,11 +163,10 @@ namespace Cysharp.Threading.Tasks
                     {
                         yield return null;
                     }
-                    else if (current is CustomYieldInstruction)
+                    else if (current is CustomYieldInstruction cyi)
                     {
                         // WWW, WaitForSecondsRealtime
-                        var e2 = UnwrapWaitCustomYieldInstruction((CustomYieldInstruction)current);
-                        while (e2.MoveNext())
+                        while (cyi.keepWaiting)
                         {
                             yield return null;
                         }
@@ -212,15 +211,6 @@ namespace Cysharp.Threading.Tasks
                 }
             }
 
-            // WWW and others as CustomYieldInstruction.
-            static IEnumerator UnwrapWaitCustomYieldInstruction(CustomYieldInstruction yieldInstruction)
-            {
-                while (yieldInstruction.keepWaiting)
-                {
-                    yield return null;
-                }
-            }
-
             static readonly FieldInfo waitForSeconds_Seconds = typeof(WaitForSeconds).GetField("m_Seconds", BindingFlags.Instance | BindingFlags.GetField | BindingFlags.NonPublic);
 
             static IEnumerator UnwrapWaitForSeconds(WaitForSeconds waitForSeconds)