diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/Linq/Merge.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/Linq/Merge.cs
index cfbcff5d..5bc7649c 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/Linq/Merge.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/Linq/Merge.cs
@@ -69,8 +69,6 @@ sealed class _Merge : MoveNextSource, IUniTaskAsyncEnumerator<T>
             readonly Queue<(T, Exception)> resultQueue = new Queue<(T, Exception)>();
             readonly CancellationToken cancellationToken;
 
-            bool allCompleted;
-
             public T Current { get; private set; }
 
             public _Merge(IUniTaskAsyncEnumerable<T>[] sources, CancellationToken cancellationToken)
@@ -100,7 +98,7 @@ public UniTask<bool> MoveNextAsync()
                     else
                     {
                         Current = queuedValue;
-                        completionSource.TrySetResult(Volatile.Read(ref allCompleted));
+                        completionSource.TrySetResult(!IsCompletedAll());
                     }
                     return new UniTask<bool>(this, completionSource.Version);
                 }
@@ -155,39 +153,22 @@ void GetResultAt(int index, UniTask<bool>.Awaiter awaiter)
                     lock (states)
                     {
                         states[index] = hasNext ? MergeSourceState.Pending : MergeSourceState.Completed;
-                        
-                        // Check to complete
-                        if (!hasNext)
-                        {
-                            allCompleted = true;
-                            for (var i = 0; i < length; i++)
-                            {
-                                if (states[i] != MergeSourceState.Completed)
-                                {
-                                    allCompleted = false;
-                                    break;
-                                }
-                            }
-                        }
                     }
                 }
                 catch (Exception ex)
                 {
-                    if (completionSource.GetStatus(completionSource.Version).IsCompleted())
+                    if (!completionSource.TrySetException(ex))
                     {
                         lock (resultQueue)
                         {
                             resultQueue.Enqueue((default, ex));
                         }
                     }
-                    else
-                    {
-                        completionSource.TrySetException(ex);
-                    }
                     return;
                 }
 
-                if (hasNext || Volatile.Read(ref allCompleted))
+                var completed = IsCompletedAll();
+                if (hasNext || completed)
                 {
                     if (completionSource.GetStatus(completionSource.Version).IsCompleted())
                     {
@@ -199,7 +180,7 @@ void GetResultAt(int index, UniTask<bool>.Awaiter awaiter)
                     else
                     {
                         Current = enumerators[index].Current;
-                        completionSource.TrySetResult(!Volatile.Read(ref allCompleted));
+                        completionSource.TrySetResult(!completed);
                     }
                 }
             }
@@ -220,6 +201,21 @@ bool TryDequeue(out T value, out Exception ex)
                 ex = default;
                 return false;
             }
-       }
+
+            bool IsCompletedAll()
+            {
+                lock (states)
+                {
+                    for (var i = 0; i < length; i++)
+                    {
+                        if (states[i] != MergeSourceState.Completed)
+                        {
+                            return false;
+                        }
+                    }
+                    return true;
+                }
+            }
+        }
     }
 }
\ No newline at end of file