diff --git a/external/mirai-core/src/markdown_data_provider.parser.cpp b/external/mirai-core/src/markdown_data_provider.parser.cpp
index 76cd36c..c8f62d4 100644
--- a/external/mirai-core/src/markdown_data_provider.parser.cpp
+++ b/external/mirai-core/src/markdown_data_provider.parser.cpp
@@ -110,18 +110,20 @@ std::string markdown_data_provider::to_markdown()
 	int next_task_index = 0;
 	int next_event_index = 0;
 
-	std::sort(_data.tasks.begin(), _data.tasks.end(), [](const task_data &t1, const task_data &t2) {
-		if (!t1.due_date.has_value() && !t2.due_date.has_value()) {
-			return false;
+	std::stable_sort(
+		_data.tasks.begin(), _data.tasks.end(), [](const task_data &t1, const task_data &t2) {
+			if (!t1.due_date.has_value() && !t2.due_date.has_value()) {
+				return false;
+			}
+			if (t1.due_date.has_value() && !t2.due_date.has_value()) {
+				return true;
+			}
+			if (!t1.due_date.has_value() && t2.due_date.has_value()) {
+				return false;
+			}
+			return t1.due_date < t2.due_date;
 		}
-		if (t1.due_date.has_value() && !t2.due_date.has_value()) {
-			return true;
-		}
-		if (!t1.due_date.has_value() && t2.due_date.has_value()) {
-			return false;
-		}
-		return t1.due_date < t2.due_date;
-	});
+	);
 
 	while (next_event_index < _data.events.size() || next_task_index < _data.tasks.size()) {
 		std::optional<class date> current_date = std::nullopt;
diff --git a/external/mirai-core/src/task.cpp b/external/mirai-core/src/task.cpp
index c095acd..26a1ad1 100644
--- a/external/mirai-core/src/task.cpp
+++ b/external/mirai-core/src/task.cpp
@@ -58,14 +58,13 @@ void task::set_title(const std::string &newTitle)
 
 void task::set_date(const date &date)
 {
-	auto emptyEventId = std::optional<std::optional<int>>(std::optional<int>(std::nullopt));
 	data_->update_task(id(), {.due_date = date});
 }
 
 void task::unschedule()
 {
-	auto emptyId = std::optional<std::optional<int>>(std::optional<int>(std::nullopt));
-	data_->update_task(id(), {.due_date = std::nullopt});
+	const std::optional<date> new_date = std::nullopt;
+	data_->update_task(id(), {.due_date = new_date});
 }
 
 void task::set_checked(bool checked)
diff --git a/src/app_logic.cpp b/src/app_logic.cpp
index 11be666..13a689e 100644
--- a/src/app_logic.cpp
+++ b/src/app_logic.cpp
@@ -190,7 +190,11 @@ void app_logic::setup_callbacks()
 		const mirai::date &date = slint_date_to_mirai_date(newTaskData.date);
 		// const auto dayOpt = source->get_day_by_date(date);
 		task->set_title(std::string(newTaskData.title));
-		task->set_date(slint_date_to_mirai_date(newTaskData.date));
+		if (newTaskData.date.day == 0) {
+			task->unschedule();
+		} else {
+			task->set_date(slint_date_to_mirai_date(newTaskData.date));
+		}
 
 		_mirai_core->save();
 		update_views();
@@ -391,18 +395,20 @@ get_all_tasks_from_sources(std::vector<std::unique_ptr<mirai::source>> &sources)
 		const auto &tasks = source->get_tasks();
 		all_tasks.insert(all_tasks.end(), tasks.begin(), tasks.end());
 	}
-	std::sort(all_tasks.begin(), all_tasks.end(), [](const mirai::task &t1, const mirai::task &t2) {
-		if (!t1.has_due_date() && !t2.has_due_date()) {
-			return false;
+	std::stable_sort(
+		all_tasks.begin(), all_tasks.end(), [](const mirai::task &t1, const mirai::task &t2) {
+			if (!t1.has_due_date() && !t2.has_due_date()) {
+				return false;
+			}
+			if (t1.has_due_date() && !t2.has_due_date()) {
+				return true;
+			}
+			if (!t1.has_due_date() && t2.has_due_date()) {
+				return false;
+			}
+			return t1.due_date() < t2.due_date();
 		}
-		if (t1.has_due_date() && !t2.has_due_date()) {
-			return true;
-		}
-		if (!t1.has_due_date() && t2.has_due_date()) {
-			return false;
-		}
-		return t1.due_date() < t2.due_date();
-	});
+	);
 	return all_tasks;
 }