diff --git a/src/akonadi/akonadiserializer.cpp b/src/akonadi/akonadiserializer.cpp
--- a/src/akonadi/akonadiserializer.cpp
+++ b/src/akonadi/akonadiserializer.cpp
@@ -33,9 +33,6 @@
 #include <kcalcore_version.h>
 #include <KMime/Message>
 #include <QMimeDatabase>
-#if KCALCORE_VERSION < QT_VERSION_CHECK(5, 6, 80)
-#include <KDateTime>
-#endif
 
 #include <numeric>
 
@@ -197,15 +194,9 @@
     task->setTitle(todo->summary());
     task->setText(todo->description());
     task->setDone(todo->isCompleted());
-#if KCALCORE_VERSION >= QT_VERSION_CHECK(5, 6, 80)
     task->setDoneDate(todo->completed().toLocalTime().date());
     task->setStartDate(todo->dtStart().toLocalTime().date());
     task->setDueDate(todo->dtDue().toLocalTime().date());
-#else
-    task->setDoneDate(todo->completed().dateTime().toLocalTime().date());
-    task->setStartDate(todo->dtStart().dateTime().toLocalTime().date());
-    task->setDueDate(todo->dtDue().dateTime().toLocalTime().date());
-#endif
     task->setProperty("itemId", item.id());
     task->setProperty("parentCollectionId", item.parentCollection().id());
     task->setProperty("todoUid", todo->uid());
@@ -270,11 +261,6 @@
     return false;
 }
 
-#if KCALCORE_VERSION >= QT_VERSION_CHECK(5, 6, 80)
-#define KDateTime QDateTime
-#endif
-
-
 Akonadi::Item Serializer::createItemFromTask(Domain::Task::Ptr task)
 {
     auto todo = KCalCore::Todo::Ptr::create();
diff --git a/src/presentation/artifactfilterproxymodel.cpp b/src/presentation/artifactfilterproxymodel.cpp
--- a/src/presentation/artifactfilterproxymodel.cpp
+++ b/src/presentation/artifactfilterproxymodel.cpp
@@ -108,12 +108,12 @@
     return QSortFilterProxyModel::filterAcceptsRow(sourceRow, sourceParent);
 }
 
-static QDate validDt(const QDate &date = QDate())
+static QDate validDate(const QDate &date = QDate())
 {
     if (date.isValid())
         return date;
 
-    return QDate(10000, 12, 31);
+    return QDate(80000, 12, 31);
 }
 
 bool ArtifactFilterProxyModel::lessThan(const QModelIndex &left, const QModelIndex &right) const
@@ -129,11 +129,11 @@
 
     // The addDays(1) is so that we sort non-tasks (e.g. notes) at the end
 
-    const QDate leftDue = leftTask ? validDt(leftTask->dueDate()) : validDt().addDays(1);
-    const QDate rightDue = rightTask ? validDt(rightTask->dueDate()) : validDt().addDays(1);
+    const QDate leftDue = leftTask ? validDate(leftTask->dueDate()) : validDate().addDays(1);
+    const QDate rightDue = rightTask ? validDate(rightTask->dueDate()) : validDate().addDays(1);
 
-    const QDate leftStart = leftTask ? validDt(leftTask->startDate()) : validDt().addDays(1);
-    const QDate rightStart = rightTask ? validDt(rightTask->startDate()) : validDt().addDays(1);
+    const QDate leftStart = leftTask ? validDate(leftTask->startDate()) : validDate().addDays(1);
+    const QDate rightStart = rightTask ? validDate(rightTask->startDate()) : validDate().addDays(1);
 
     return leftDue < rightDue
         || leftStart < rightStart;
diff --git a/src/utils/datetime.h b/src/utils/datetime.h
--- a/src/utils/datetime.h
+++ b/src/utils/datetime.h
@@ -31,7 +31,6 @@
 
 namespace DateTime
 {
-    QDateTime currentDateTime();
     QDate currentDate();
 }
 
diff --git a/src/utils/datetime.cpp b/src/utils/datetime.cpp
--- a/src/utils/datetime.cpp
+++ b/src/utils/datetime.cpp
@@ -27,14 +27,6 @@
 
 using namespace Utils;
 
-QDateTime DateTime::currentDateTime()
-{
-    QByteArray overrideDatetime = qgetenv("ZANSHIN_OVERRIDE_DATETIME");
-    QDateTime customDateTime = QDateTime::fromString(QString::fromLocal8Bit(overrideDatetime), Qt::ISODate);
-
-    return customDateTime.isValid() ? customDateTime : QDateTime::currentDateTime();
-}
-
 QDate DateTime::currentDate()
 {
     QByteArray overrideDate = qgetenv("ZANSHIN_OVERRIDE_DATE");
diff --git a/tests/testlib/gentodo.cpp b/tests/testlib/gentodo.cpp
--- a/tests/testlib/gentodo.cpp
+++ b/tests/testlib/gentodo.cpp
@@ -25,7 +25,6 @@
 
 #include <KCalCore/Todo>
 #include <QDateTime>
-#include <kcalcore_version.h>
 
 using namespace Testlib;
 
diff --git a/tests/units/akonadi/akonadiserializertest.cpp b/tests/units/akonadi/akonadiserializertest.cpp
--- a/tests/units/akonadi/akonadiserializertest.cpp
+++ b/tests/units/akonadi/akonadiserializertest.cpp
@@ -904,11 +904,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         todo->setSummary(QStringLiteral("summary"));
-#if KCALCORE_VERSION >= QT_VERSION_CHECK(5, 6, 80)
         todo->setDtStart(QDateTime(startDate));
-#else
-        todo->setDtStart(KDateTime(startDate, KDateTime::UTC));
-#endif
         todo->recurrence()->setMonthly(1);
 
         // ... as payload of an item...
@@ -1239,24 +1235,13 @@
         QCOMPARE(todo->summary(), summary);
         QCOMPARE(todo->description(), content);
         QCOMPARE(todo->isCompleted(), isDone);
-#if KCALCORE_VERSION >= QT_VERSION_CHECK(5, 6, 80)
         QCOMPARE(todo->completed().toLocalTime().date(), doneDate);
         QCOMPARE(todo->dtStart().toLocalTime().date(), startDate);
         QCOMPARE(todo->dtDue().toLocalTime().date(), dueDate);
         if (todo->dtStart().isValid()) {
             QCOMPARE(int(todo->dtStart().timeSpec()), int(Qt::LocalTime));
         }
         QVERIFY(todo->allDay()); // this is always true currently...
-#else
-        QCOMPARE(todo->completed().dateTime().date(), doneDate);
-        QCOMPARE(todo->dtStart().dateTime().date(), startDate);
-        QCOMPARE(todo->dtDue().dateTime().date(), dueDate);
-        if (todo->dtStart().isValid()) {
-            QCOMPARE(int(todo->dtStart().timeType()), int(KDateTime::LocalTime));
-        }
-        QCOMPARE(todo->dtStart().isDateOnly(), todo->allDay());
-
-#endif
         const ushort expectedRecurrence = recurrence == Domain::Task::NoRecurrence ? KCalCore::Recurrence::rNone
                                         : recurrence == Domain::Task::RecursDaily ? KCalCore::Recurrence::rDaily
                                         : recurrence == Domain::Task::RecursWeekly ? KCalCore::Recurrence::rWeekly
diff --git a/tests/units/utils/datetimetest.cpp b/tests/units/utils/datetimetest.cpp
--- a/tests/units/utils/datetimetest.cpp
+++ b/tests/units/utils/datetimetest.cpp
@@ -31,44 +31,6 @@
 {
     Q_OBJECT
 private slots:
-    void shouldNotOverrideCurrentDateTime()
-    {
-        // GIVEN
-        const auto todayDate = QDateTime::currentDateTime();
-
-        // WHEN
-        const QDateTime zanshinDate = DateTime::currentDateTime();
-
-        // THEN
-        QCOMPARE(zanshinDate.date(), todayDate.date());
-    }
-
-    void shouldOverrideCurrentDateTime()
-    {
-        // GIVEN
-        const QByteArray dateExpected = "2015-03-10";
-        qputenv("ZANSHIN_OVERRIDE_DATETIME", dateExpected);
-
-        // WHEN
-        const QDateTime zanshinDate = DateTime::currentDateTime();
-
-        // THEN
-        QCOMPARE(zanshinDate.date(), QDateTime::fromString(QString::fromLocal8Bit(dateExpected), Qt::ISODate).date());
-    }
-
-    void shouldNotOverrideCurrentDateTimeWhenInvalidDate()
-    {
-        // GIVEN
-        const QByteArray dateExpected = "Invalid!";
-        qputenv("ZANSHIN_OVERRIDE_DATETIME", dateExpected);
-
-        // WHEN
-        const QDateTime zanshinDate = DateTime::currentDateTime();
-
-        // THEN
-        QCOMPARE(zanshinDate.date(), QDateTime::currentDateTime().date());
-    }
-
     void shouldNotOverrideCurrentDate()
     {
         // GIVEN