diff --git a/common/locales/en/api-v3.json b/common/locales/en/api-v3.json
index d9fb392743..9f4346c414 100644
--- a/common/locales/en/api-v3.json
+++ b/common/locales/en/api-v3.json
@@ -22,5 +22,6 @@
   "checklistOnlyDailyTodo": "Checklists are supported only on dailies and todos",
   "checklistItemNotFound": "No checklist item was wound with given id.",
   "itemIdRequired": "\"itemId\" must be a valid UUID",
-  "positionRequired": "\"position\" is required and must be a number."
+  "positionRequired": "\"position\" is required and must be a number.",
+  "cantMoveCompletedTodo": "Can't move a completed todo."
 }
diff --git a/website/src/controllers/api-v3/tasks.js b/website/src/controllers/api-v3/tasks.js
index c6209de2a4..e4ba525115 100644
--- a/website/src/controllers/api-v3/tasks.js
+++ b/website/src/controllers/api-v3/tasks.js
@@ -172,6 +172,7 @@ api.moveTask = {
     }).exec()
     .then((task) => {
       if (!task) throw new NotFound(res.t('taskNotFound'));
+      if (task.type === 'todo' && task.completed) throw new NotFound(res.t('cantMoveCompletedTodo'));
       let order = user.tasksOrder[`${task.type}s`];
       let currentIndex = order.indexOf(task._id);