diff --git a/InServiceQue.InMemory/TaskRepositoryInMemory.cs b/InServiceQue.InMemory/TaskRepositoryInMemory.cs
index e208dd4..0eeb2ce 100644
--- a/InServiceQue.InMemory/TaskRepositoryInMemory.cs
+++ b/InServiceQue.InMemory/TaskRepositoryInMemory.cs
@@ -1,4 +1,3 @@
-using System.Collections.Concurrent;
 using System.Data;
 using InServiceQue.Core.Models;
 using InServiceQue.Core.Repositories;
@@ -7,9 +6,9 @@ namespace InServiceQue.InMemory;
 
 public class TaskRepositoryInMemory: ITaskRepository
 {
-    //todo: concurrent access here
+    private static object _lockObject = new();
     private static int _currentShard;
-    private static ConcurrentDictionary<string, ConcurrentQueue<QueueTask>> _quesByType = new();
+    private static Dictionary<string, Queue<QueueTask>> _quesByType = new();
     public void Dispose()
     {
         // TODO release managed resources here
@@ -17,22 +16,22 @@ public class TaskRepositoryInMemory: ITaskRepository
 
     public void Insert(QueueTask task)
     {
-        if (_quesByType.ContainsKey(task.TaskType))
+        lock (_lockObject)
         {
-            _quesByType.AddOrUpdate(task.TaskType, 
-                (t) => new ConcurrentQueue<QueueTask>(new[] { task }), 
-                (t, queue) =>
-                {
-                    queue.Enqueue(task);
-                    return queue;
-                }
-            );
+            if (_quesByType.ContainsKey(task.TaskType))
+            {
+                _quesByType[task.TaskType].Enqueue(task);
+            }
+            else
+            {
+                _quesByType.Add(task.TaskType, new Queue<QueueTask>(new []{task}));
+            }
+            
         }
     }
 
     public async Task InsertAsync(QueueTask task)
     {
-        
         Insert(task);
         await Task.CompletedTask;
     }
@@ -84,26 +83,27 @@ public class TaskRepositoryInMemory: ITaskRepository
     public QueueTask? GetNextTaskRolling()
     {
         QueueTask? task = null;
-        var topicsCount = _quesByType.Count;
-        for (int i = 0; i < topicsCount; i++)
+        lock (_lockObject)
         {
-            //todo: concurrent access
-            if (i == _currentShard)
+            var topicsCount = _quesByType.Count;
+            for (int i = 0; i < topicsCount; i++)
             {
-                var keyValuePair = _quesByType.ToArray()[i];
-                var que = keyValuePair.Value;
-                que.TryDequeue(out task);
-
-                if (que.IsEmpty)
+                if (i == _currentShard)
                 {
-                    _quesByType.TryRemove(keyValuePair);
-                }
+                    var keyValuePair = _quesByType.ToArray()[i];
+                    var que = keyValuePair.Value;
+                    task = que.Dequeue();
 
-                break;
+                    if (!que.Any())
+                    {
+                        _quesByType.Remove(keyValuePair.Key);
+                    }
+                    break;
+                }
             }
+            
+            _currentShard = _currentShard == topicsCount - 1 ? 0 : _currentShard + 1;
         }
-        //todo: concurrent access
-        _currentShard = _currentShard == topicsCount - 1 ? 0 : _currentShard + 1;
         
         return task;
     }
@@ -116,11 +116,15 @@ public class TaskRepositoryInMemory: ITaskRepository
             return await Task.FromResult(GetNextTaskRolling());
         
         QueueTask? task = null;
-        if (_quesByType.TryGetValue(taskType, out var que))
+        lock (_lockObject)
         {
-            que.TryDequeue(out task);
+            if (_quesByType.TryGetValue(taskType, out var que))
+            {
+                que.TryDequeue(out task);
+            }
         }
         
+        
         return await Task.FromResult(task);
     }
 
diff --git a/InServiceQue.Sample/Program.cs b/InServiceQue.Sample/Program.cs
index 4a688e4..a4b74bd 100644
--- a/InServiceQue.Sample/Program.cs
+++ b/InServiceQue.Sample/Program.cs
@@ -4,6 +4,7 @@ using InServiceQue.Core.Repositories;
 using InServiceQue.InMemory;
 using InServiceQue.Sample;
 using InServiceQue.Services;
+using Microsoft.AspNetCore.Http.HttpResults;
 using Microsoft.AspNetCore.Mvc;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -16,12 +17,18 @@ var app = builder.Build();
 
 app.MapGet("/", async (string msg) =>
 {
-    var taskRepository = app.Services.GetService<IQueueClient>();
-    await taskRepository.AddTaskAsync(new QueueTask(new SendMessageTask(new SendMessagePayload()
+    if (!string.IsNullOrEmpty(msg))
     {
-        From = "John", To = "Esther", Message = msg
-    })));
-    await taskRepository.AddTaskAsync(new QueueTask(new OtherMessageTask(msg)));
+        var taskRepository = app.Services.GetService<IQueueClient>();
+        await taskRepository.AddTaskAsync(new SendMessageTask(new SendMessagePayload()
+        {
+            From = "John", To = "Esther", Message = msg
+        }));
+        await taskRepository.AddTaskAsync(new OtherMessageTask(msg));
+        
+        return new OkResult();
+    }
+
     return new OkResult();
 });
 
diff --git a/InServiceQue/Services/QueueClient.cs b/InServiceQue/Services/QueueClient.cs
index cc40e59..de4372c 100644
--- a/InServiceQue/Services/QueueClient.cs
+++ b/InServiceQue/Services/QueueClient.cs
@@ -6,7 +6,12 @@ namespace InServiceQue.Services;
 public class QueueClient: IQueueClient
 {
     private readonly ITaskRepository _repository;
-    
+
+    public QueueClient(ITaskRepository repository)
+    {
+        _repository = repository;
+    }
+
     public void AddTask(IQueueTask task)
     {
         var queueTask = new QueueTask(task);