diff --git a/src/akonadi/akonaditaskqueries.cpp b/src/akonadi/akonaditaskqueries.cpp
--- a/src/akonadi/akonaditaskqueries.cpp
+++ b/src/akonadi/akonaditaskqueries.cpp
@@ -111,7 +111,7 @@
     }
 
     auto fetch = m_helpers->fetchItems(StorageInterface::Tasks);
-    auto predicate = [this] (const Akonadi::Item &item) {
+    auto isWorkdayItem = [this] (const Akonadi::Item &item) {
         if (!m_serializer->isTaskItem(item))
             return false;
 
@@ -131,6 +131,30 @@
         else
             return pastStartDate || pastDueDate;
     };
+    auto predicate = [this, isWorkdayItem] (const Akonadi::Item &item) {
+        if (!isWorkdayItem(item))
+            return false;
+
+        const auto items = m_cache->items(item.parentCollection());
+        auto currentItem = item;
+        auto parentUid = m_serializer->relatedUidFromItem(currentItem);
+        while (!parentUid.isEmpty()) {
+            const auto parent = std::find_if(items.cbegin(), items.cend(),
+                                             [this, parentUid] (const Akonadi::Item &item) {
+                                                 return m_serializer->itemUid(item) == parentUid;
+                                             });
+            if (parent == items.cend())
+                break;
+
+            if (isWorkdayItem(*parent))
+                return false;
+
+            currentItem = *parent;
+            parentUid = m_serializer->relatedUidFromItem(currentItem);
+        }
+
+        return true;
+    };
     m_integrator->bind("TaskQueries::findWorkdayTopLevel", m_findWorkdayTopLevel, fetch, predicate);
     return m_findWorkdayTopLevel->result();
 }
diff --git a/tests/units/akonadi/akonaditaskqueriestest.cpp b/tests/units/akonadi/akonaditaskqueriestest.cpp
--- a/tests/units/akonadi/akonaditaskqueriestest.cpp
+++ b/tests/units/akonadi/akonaditaskqueriestest.cpp
@@ -1571,6 +1571,51 @@
         QCOMPARE(result->data().at(0)->title(), QStringLiteral("42"));
         QCOMPARE(result->data().at(1)->title(), QStringLiteral("43"));
     }
+
+    void shouldNotListWorkdayTasksTwiceIfTheyHaveAParentInWorkday()
+    {
+        // GIVEN
+        const auto today = Utils::DateTime::currentDateTime();
+        AkonadiFakeData data;
+
+        // One top level collection
+        data.createCollection(GenCollection().withId(42).withRootAsParent().withTaskContent());
+
+        // One context tag
+        data.createTag(GenTag().withId(42).withName(QStringLiteral("42")).asContext());
+
+        // Five tasks in the collection, two start today, three not, all forming an ancestry line
+        data.createItem(GenTodo().withParent(42).withId(42).withTitle(QStringLiteral("42")).withUid("42"));
+        data.createItem(GenTodo().withParent(42).withId(43).withTitle(QStringLiteral("43")).withUid("43").withParentUid("42").withStartDate(today.addSecs(300)));
+        data.createItem(GenTodo().withParent(42).withId(44).withTitle(QStringLiteral("44")).withUid("44").withParentUid("43"));
+        data.createItem(GenTodo().withParent(42).withId(45).withTitle(QStringLiteral("45")).withUid("45").withParentUid("44").withStartDate(today.addSecs(300)));
+        data.createItem(GenTodo().withParent(42).withId(46).withTitle(QStringLiteral("46")).withUid("46").withParentUid("45"));
+
+        // WHEN
+        auto serializer = Akonadi::Serializer::Ptr(new Akonadi::Serializer);
+        auto cache = Akonadi::Cache::Ptr::create(serializer, Akonadi::MonitorInterface::Ptr(data.createMonitor()));
+        QScopedPointer<Domain::TaskQueries> queries(new Akonadi::TaskQueries(createCachingStorage(data, cache),
+                                                                             Akonadi::Serializer::Ptr(new Akonadi::Serializer),
+                                                                             Akonadi::MonitorInterface::Ptr(data.createMonitor()),
+                                                                             cache));
+        auto result = queries->findWorkdayTopLevel();
+        result->data();
+        result = queries->findWorkdayTopLevel(); // Should not cause any problem or wrong data
+
+        // THEN
+        QVERIFY(result->data().isEmpty());
+        TestHelpers::waitForEmptyJobQueue();
+
+        QCOMPARE(result->data().size(), 1);
+        QCOMPARE(result->data().at(0)->title(), QStringLiteral("43"));
+
+        // Should not change anything
+        result = queries->findWorkdayTopLevel();
+        TestHelpers::waitForEmptyJobQueue();
+
+        QCOMPARE(result->data().size(), 1);
+        QCOMPARE(result->data().at(0)->title(), QStringLiteral("43"));
+    }
 };
 
 ZANSHIN_TEST_MAIN(AkonadiTaskQueriesTest)