diff --git a/Recyclable.Collections/Parallel/IndexOfSynchronizationContext.cs b/Recyclable.Collections/Parallel/IndexOfSynchronizationContext.cs
index 4a53190..99fcd77 100644
--- a/Recyclable.Collections/Parallel/IndexOfSynchronizationContext.cs
+++ b/Recyclable.Collections/Parallel/IndexOfSynchronizationContext.cs
@@ -3,6 +3,10 @@ namespace Recyclable.Collections.Parallel
 	public sealed class IndexOfSynchronizationContext
 	{
 		private readonly SpinWait _participantsSpinWait = new();
+		private readonly SpinLock _participantsSpinLock = new(false);
+		private readonly SpinLock _indexOfSpinLock = new(false);
+		private bool _indexOfLockTaken;
+
 
 		internal bool _isItemFound;
 		internal int _participants;
@@ -10,12 +14,29 @@ namespace Recyclable.Collections.Parallel
 
 		public void AddParticipant()
 		{
-			_ = Interlocked.Increment(ref _participants);
+			bool lockTaken = false;
+			_participantsSpinLock.Enter(ref lockTaken);
+			_participants++;
+			if (lockTaken)
+			{
+				_participantsSpinLock.Exit(false);
+			}
 		}
 
 		public void AddParticipants(int newParticipants)
 		{
-			_ = Interlocked.Add(ref _participants, newParticipants);
+			bool lockTaken = false;
+			_participantsSpinLock.Enter(ref lockTaken);
+			_participants += newParticipants;
+			if (lockTaken)
+			{
+				_participantsSpinLock.Exit(false);
+			}
+		}
+
+		public void Lock()
+		{
+			_indexOfSpinLock.Enter(ref _indexOfLockTaken);
 		}
 
 		public void RemoveParticipants(int participantsToRemove)
@@ -25,7 +46,13 @@ namespace Recyclable.Collections.Parallel
 				ThrowNotEnoughParticipants();
 			}
 
-			_ = Interlocked.Add(ref _participants, -participantsToRemove);
+			bool lockTaken = false;
+			_participantsSpinLock.Enter(ref lockTaken);
+			_participants -= participantsToRemove;
+			if (lockTaken)
+			{
+				_participantsSpinLock.Exit(false);
+			}
 		}
 
 		public void RemoveParticipant()
@@ -35,7 +62,13 @@ namespace Recyclable.Collections.Parallel
 				ThrowNoMoreParticipants();
 			}
 
-			_ = Interlocked.Decrement(ref _participants);
+			bool lockTaken = false;
+			_participantsSpinLock.Enter(ref lockTaken);
+			_participants--;
+			if (lockTaken)
+			{
+				_participantsSpinLock.Exit(false);
+			}
 		}
 
 		public void SignalAndWait()
@@ -45,13 +78,28 @@ namespace Recyclable.Collections.Parallel
 				ThrowNoMoreParticipants();
 			}
 
-			_ = Interlocked.Decrement(ref _participants);
+			bool lockTaken = false;
+			_participantsSpinLock.Enter(ref lockTaken);
+			_participants--;
+			if (lockTaken)
+			{
+				_participantsSpinLock.Exit(false);
+			}
+
 			while (_participants > 0)
 			{
 				_participantsSpinWait.SpinOnce();
 			}
 		}
 
+		public void Unlock()
+		{
+			if (_indexOfLockTaken)
+			{
+				_indexOfSpinLock.Exit(false);
+			}
+		}
+
 		private static void ThrowNotEnoughParticipants() => throw new InvalidOperationException("Participant cannot be removed, because there are not enough participants.");
 		private static void ThrowNoMoreParticipants() => throw new InvalidOperationException("Participant cannot be removed, because there are no more participants.");
 
diff --git a/Recyclable.Collections/RecyclableLongList.IndexOfHelpers.cs b/Recyclable.Collections/RecyclableLongList.IndexOfHelpers.cs
index d84126d..62d367b 100644
--- a/Recyclable.Collections/RecyclableLongList.IndexOfHelpers.cs
+++ b/Recyclable.Collections/RecyclableLongList.IndexOfHelpers.cs
@@ -25,7 +25,9 @@ namespace Recyclable.Collections
 					else if (index >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, (blockIndex << list._blockSizePow2BitShift) + index);
+						context.Lock();
+						context.FoundItemIndex = ((long)blockIndex << list._blockSizePow2BitShift) + index;
+						context.Unlock();
 						return;
 					}
 
@@ -37,7 +39,9 @@ namespace Recyclable.Collections
 					else if (index >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, ((blockIndex + 1) << list._blockSizePow2BitShift) + index);
+						context.Lock();
+						context.FoundItemIndex = ((long)(blockIndex + 1) << list._blockSizePow2BitShift) + index;
+						context.Unlock();
 						return;
 					}
 
@@ -49,7 +53,9 @@ namespace Recyclable.Collections
 					else if (index >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, ((blockIndex + 2) << list._blockSizePow2BitShift) + index);
+						context.Lock();
+						context.FoundItemIndex = ((long)(blockIndex + 2) << list._blockSizePow2BitShift) + index;
+						context.Unlock();
 						return;
 					}
 
@@ -57,7 +63,9 @@ namespace Recyclable.Collections
 					if (!context._isItemFound && index >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, ((blockIndex + 3) << list._blockSizePow2BitShift) + index);
+						context.Lock();
+						context.FoundItemIndex = ((long)(blockIndex + 3) << list._blockSizePow2BitShift) + index;
+						context.Unlock();
 					}
 				}
 				catch (Exception e)
@@ -87,7 +95,9 @@ namespace Recyclable.Collections
 					if (!context._isItemFound && index >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, (blockIndex << list._blockSizePow2BitShift) + index);
+						context.Lock();
+						context.FoundItemIndex = ((long)blockIndex << list._blockSizePow2BitShift) + index;
+						context.Unlock();
 					}
 				}
 				catch (Exception e)
@@ -176,7 +186,9 @@ namespace Recyclable.Collections
 					if (!context._isItemFound && itemIndex >= 0)
 					{
 						context._isItemFound = true;
-						_ = Interlocked.Exchange(ref context.FoundItemIndex, ((long)blockIndex << list._blockSizePow2BitShift) + itemIndex);
+						context.Lock();
+						context.FoundItemIndex = ((long)blockIndex << list._blockSizePow2BitShift) + itemIndex;
+						context.Unlock();
 					}
 				}
 
@@ -249,16 +261,9 @@ namespace Recyclable.Collections
 					}
 				}
 
-				//if (blockIndex == list._lastBlockWithData)
-				//{
-					itemIndex = list._nextItemIndex != 0
-						? Array.IndexOf(memoryBlocksSpan[list._lastBlockWithData], item, 0, list._nextItemIndex)
-						: Array.IndexOf(memoryBlocksSpan[list._lastBlockWithData], item, 0, list._blockSize);
-				//}
-				//else
-				//{
-				//	return RecyclableDefaults.ItemNotFoundIndexLong;
-				//}
+				itemIndex = list._nextItemIndex != 0
+					? Array.IndexOf(memoryBlocksSpan[list._lastBlockWithData], item, 0, list._nextItemIndex)
+					: Array.IndexOf(memoryBlocksSpan[list._lastBlockWithData], item, 0, list._blockSize);
 
 				return itemIndex >= 0 ? itemIndex + ((long)list._lastBlockWithData << list._blockSizePow2BitShift) : RecyclableDefaults.ItemNotFoundIndexLong;
 			}