diff --git a/src/Mcp/Tool/Task/CreateTaskTool.php b/src/Mcp/Tool/Task/CreateTaskTool.php
index 716de42..9e71ea3 100644
--- a/src/Mcp/Tool/Task/CreateTaskTool.php
+++ b/src/Mcp/Tool/Task/CreateTaskTool.php
@@ -54,7 +54,7 @@ class CreateTaskTool
         $task = new Task();
         $task->setProject($project);
         $task->setTitle($title);
-        $task->setNumber($this->taskRepository->findMaxNumberByProject($project) + 1);
+        $task->setNumber($this->taskRepository->findMaxNumberByProjectForUpdate($project) + 1);
 
         if (null !== $description) {
             $task->setDescription($description);
diff --git a/src/Repository/TaskRepository.php b/src/Repository/TaskRepository.php
index d2fb050..99857a5 100644
--- a/src/Repository/TaskRepository.php
+++ b/src/Repository/TaskRepository.php
@@ -28,7 +28,7 @@ class TaskRepository extends ServiceEntityRepository
         $conn = $this->getEntityManager()->getConnection();
 
         $result = $conn->fetchOne(
-            'SELECT COALESCE(MAX(number), 0) FROM task WHERE project_id = :project FOR UPDATE',
+            'SELECT COALESCE(MAX(number), 0) FROM task WHERE project_id = :project',
             ['project' => $project->getId()],
         );