Index: src/akonadi/akonadiserializer.h
===================================================================
--- src/akonadi/akonadiserializer.h
+++ src/akonadi/akonadiserializer.h
@@ -75,6 +75,13 @@
     void addContextToTask(Domain::Context::Ptr context, Akonadi::Item item) override;
     void removeContextFromTask(Domain::Context::Ptr context, Akonadi::Item item) override;
     QString contextUid(Akonadi::Item item) override;
+
+    static QByteArray customPropertyAppName();
+    static QByteArray customPropertyIsProject();
+    static QByteArray customPropertyIsContext();
+    static QByteArray customPropertyIsRunning();
+    static QByteArray customPropertyContextList();
+
 };
 
 }
Index: src/akonadi/akonadiserializer.cpp
===================================================================
--- src/akonadi/akonadiserializer.cpp
+++ src/akonadi/akonadiserializer.cpp
@@ -40,9 +40,6 @@
 
 using namespace Akonadi;
 
-static const char s_contextListProperty[] = "ContextList";
-static const char s_appName[] = "Zanshin";
-
 Serializer::Serializer()
 {
 }
@@ -183,7 +180,7 @@
     task->setProperty("parentCollectionId", item.parentCollection().id());
     task->setProperty("todoUid", todo->uid());
     task->setProperty("relatedUid", todo->relatedTo());
-    task->setRunning(todo->customProperty("Zanshin", "Running") == QLatin1String("1"));
+    task->setRunning(todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning()) == QLatin1String("1"));
 
     switch (todo->recurrence()->recurrenceType()) {
     case KCalCore::Recurrence::rDaily:
@@ -281,9 +278,9 @@
     }
 
     if (task->isRunning()) {
-        todo->setCustomProperty("Zanshin", "Running", "1");
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning(), "1");
     } else {
-        todo->removeCustomProperty("Zanshin", "Running");
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning());
     }
 
     // Needs to be done after all other dates are positioned
@@ -349,7 +346,7 @@
 
     auto todo = item.payload<KCalCore::Todo::Ptr>();
     todo->setRelatedTo(QString());
-    todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+    todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 }
 
 void Serializer::clearItem(Akonadi::Item *item)
@@ -359,7 +356,7 @@
         return;
 
     auto todo = item->payload<KCalCore::Todo::Ptr>();
-    todo->removeCustomProperty(s_appName, s_contextListProperty);
+    todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
 }
 
 Akonadi::Item::List Serializer::filterDescendantItems(const Akonadi::Item::List &potentialChildren, const Akonadi::Item &ancestorItem)
@@ -398,7 +395,7 @@
         return false;
 
     auto todo = item.payload<KCalCore::Todo::Ptr>();
-    return !todo->customProperty(s_appName, "Project").isEmpty();
+    return !todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty();
 }
 
 Domain::Project::Ptr Serializer::createProjectFromItem(Item item)
@@ -429,7 +426,7 @@
     auto todo = KCalCore::Todo::Ptr::create();
 
     todo->setSummary(project->name());
-    todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+    todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
     if (project->property("todoUid").isValid()) {
         todo->setUid(project->property("todoUid").toString());
@@ -468,7 +465,7 @@
 
     auto contextUid = context->property("todoUid").toString();
     auto todo = item.payload<KCalCore::Todo::Ptr>();
-    const QString contexts = todo->customProperty(s_appName, s_contextListProperty);
+    const QString contexts = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     const QStringList contextList = contexts.split(',');
     return contextList.contains(contextUid);
 }
@@ -479,7 +476,7 @@
         return false;
 
     auto todo = item.payload<KCalCore::Todo::Ptr>();
-    return !todo->customProperty(s_appName, "Context").isEmpty();
+    return !todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()).isEmpty();
 }
 
 Domain::Context::Ptr Serializer::createContextFromItem(Item item)
@@ -497,7 +494,7 @@
     auto todo = KCalCore::Todo::Ptr::create();
 
     todo->setSummary(context->name());
-    todo->setCustomProperty(s_appName, "Context", QStringLiteral("1"));
+    todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext(), QStringLiteral("1"));
 
     if (context->property("todoUid").isValid()) {
         todo->setUid(context->property("todoUid").toString());
@@ -542,11 +539,11 @@
         return;
 
     auto contextUid = context->property("todoUid").toString();
-    const QString contexts = todo->customProperty(s_appName, s_contextListProperty);
+    const QString contexts = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     QStringList contextList = contexts.split(',', QString::SkipEmptyParts);
     if (!contextList.contains(contextUid))
         contextList.append(contextUid);
-    todo->setCustomProperty(s_appName, s_contextListProperty, contextList.join(','));
+    todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextList.join(','));
 
     item.setPayload<KCalCore::Todo::Ptr>(todo);
 }
@@ -564,13 +561,13 @@
         return;
 
     auto contextUid = context->property("todoUid").toString();
-    const QString contexts = todo->customProperty(s_appName, s_contextListProperty);
+    const QString contexts = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     QStringList contextList = contexts.split(',', QString::SkipEmptyParts);
     contextList.removeAll(contextUid);
     if (contextList.isEmpty())
-        todo->removeCustomProperty(s_appName, s_contextListProperty);
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     else
-        todo->setCustomProperty(s_appName, s_contextListProperty, contextList.join(','));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextList.join(','));
 
     item.setPayload<KCalCore::Todo::Ptr>(todo);
 }
@@ -583,3 +580,32 @@
     auto todo = item.payload<KCalCore::Todo::Ptr>();
     return todo->uid();
 }
+
+// KCalCore's CustomProperties doesn't implement case insensitivity
+// and some CALDAV servers make everything uppercase. So do like most of kdepim
+// and use uppercase property names.
+
+QByteArray Serializer::customPropertyAppName()
+{
+    return QByteArrayLiteral("ZANSHIN");
+}
+
+QByteArray Serializer::customPropertyIsProject()
+{
+    return QByteArrayLiteral("PROJECT");
+}
+
+QByteArray Serializer::customPropertyIsContext()
+{
+    return QByteArrayLiteral("CONTEXT");
+}
+
+QByteArray Serializer::customPropertyIsRunning()
+{
+    return QByteArrayLiteral("RUNNING");
+}
+
+QByteArray Serializer::customPropertyContextList()
+{
+    return QByteArrayLiteral("CONTEXTLIST");
+}
Index: src/zanshin/migrator/zanshin021migrator.cpp
===================================================================
--- src/zanshin/migrator/zanshin021migrator.cpp
+++ src/zanshin/migrator/zanshin021migrator.cpp
@@ -24,22 +24,25 @@
 #include "zanshin021migrator.h"
 #include <akonadi/akonadicollectionfetchjobinterface.h>
 #include <akonadi/akonadiitemfetchjobinterface.h>
+#include <akonadi/akonadiserializer.h>
 
 #include <AkonadiCore/TransactionSequence>
 #include <AkonadiCore/ItemModifyJob>
 
 #include <QStringList>
 #include <KCalCore/Todo>
 
+using Akonadi::Serializer;
+
 Zanshin021Migrator::Zanshin021Migrator()
 {
 
 }
 
 bool Zanshin021Migrator::isProject(const Akonadi::Item& item)
 {
     // same as Serializer::isProject, but we don't need the serializer here...
-    return item.hasPayload<KCalCore::Todo::Ptr>() && !item.payload<KCalCore::Todo::Ptr>()->customProperty("Zanshin", "Project").isEmpty();
+    return item.hasPayload<KCalCore::Todo::Ptr>() && !item.payload<KCalCore::Todo::Ptr>()->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty();
 }
 
 
@@ -71,7 +74,7 @@
     Akonadi::Item &item = seenItem.item();
     if (!isProject(item)) {
         auto todo = item.payload<KCalCore::Todo::Ptr>();
-        todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
         item.setPayload(todo);
         seenItem.setDirty();
         qDebug() << "Marking as project:" << item.id() << item.remoteId() << todo->summary();
Index: src/zanshin/migrator/zanshincontextitemsmigrator.cpp
===================================================================
--- src/zanshin/migrator/zanshincontextitemsmigrator.cpp
+++ src/zanshin/migrator/zanshincontextitemsmigrator.cpp
@@ -32,6 +32,8 @@
 #include <QStringList>
 #include <KCalCore/Todo>
 
+using Akonadi::Serializer;
+
 static const char s_contextTagType[] = "Zanshin-Context";
 
 ZanshinContextItemsMigrator::ZanshinContextItemsMigrator()
@@ -55,13 +57,13 @@
         foreach (const Akonadi::Item &item, items) {
             if (item.hasPayload<KCalCore::Todo::Ptr>()) {
                 auto todo = item.payload<KCalCore::Todo::Ptr>();
-                if (which == WhichItems::TasksToConvert && !todo->customProperty("Zanshin", "ContextList").isEmpty()) {
+                if (which == WhichItems::TasksToConvert && !todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()).isEmpty()) {
                     // This folder was already migrated, skip it
                     hasTaskToConvert = false;
                     qDebug() << "Detected an already converted task" << todo->uid();
                     break;
                 }
-                const bool isContext = !todo->customProperty("Zanshin", "Context").isEmpty();
+                const bool isContext = !todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()).isEmpty();
                 if ((isContext && which == WhichItems::OnlyContexts) ||
                         (!isContext && which == WhichItems::TasksToConvert) ||
                         (!isContext && which == WhichItems::AllTasks)) {
Index: tests/features/testenv/data/testdata.xml
===================================================================
--- tests/features/testenv/data/testdata.xml
+++ tests/features/testenv/data/testdata.xml
@@ -17,7 +17,7 @@
 SUMMARY:Buy kiwis&#xd;
 DUE;VALUE=DATE:20150310&#xd;
 PERCENT-COMPLETE:0&#xd;
-X-KDE-Zanshin-ContextList:errands-context&#xd;
+X-KDE-ZANSHIN-CONTEXTLIST:errands-context&#xd;
 END:VTODO&#xd;
 
 END:VCALENDAR</payload>
@@ -91,7 +91,7 @@
 CREATED:20120322T164413Z&#xd;
 UID:06ff6f36-f0a0-47b9-8c77-7a18207eb5ea&#xd;
 LAST-MODIFIED:20120322T164413Z&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 SUMMARY:Read List&#xd;
 PERCENT-COMPLETE:0&#xd;
 END:VTODO&#xd;
@@ -160,7 +160,7 @@
 UID:f1a30fc7-d941-4c81-a083-7c1e9657ae24&#xd;
 LAST-MODIFIED:20120322T164413Z&#xd;
 SUMMARY: Prepare talk about TDD&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 PERCENT-COMPLETE:0&#xd;
 END:VTODO&#xd;
 
@@ -301,7 +301,7 @@
 CREATED:20120322T164413Z&#xd;
 UID:04944d0e-43a5-4cc1-9ca0-bc3200981879&#xd;
 LAST-MODIFIED:20120322T164413Z&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 SUMMARY:Backlog&#xd;
 PERCENT-COMPLETE:0&#xd;
 END:VTODO&#xd;
@@ -333,7 +333,7 @@
 BEGIN:VTODO&#xd;
 CREATED:20190317T162551Z&#xd;
 UID:errands-context&#xd;
-X-KDE-Zanshin-Context:1&#xd;
+X-KDE-ZANSHIN-CONTEXT:1&#xd;
 LAST-MODIFIED:20140317T162551Z&#xd;
 SUMMARY:Errands&#xd;
 END:VTODO&#xd;
@@ -348,7 +348,7 @@
 BEGIN:VTODO&#xd;
 CREATED:20190317T162551Z&#xd;
 UID:online-context&#xd;
-X-KDE-Zanshin-Context:1&#xd;
+X-KDE-ZANSHIN-CONTEXT:1&#xd;
 LAST-MODIFIED:20140317T162551Z&#xd;
 SUMMARY:Online&#xd;
 END:VTODO&#xd;
Index: tests/testlib/akonadifakedata.cpp
===================================================================
--- tests/testlib/akonadifakedata.cpp
+++ tests/testlib/akonadifakedata.cpp
@@ -27,11 +27,13 @@
 
 #include <KCalCore/Todo>
 
+#include "akonadi/akonadiserializer.h"
 #include "akonadi/akonadiapplicationselectedattribute.h"
 
 #include <algorithm>
 
 using namespace Testlib;
+using Akonadi::Serializer;
 
 template<class Entity>
 static Akonadi::Collection::Id findParentId(const Entity &entity)
@@ -41,16 +43,13 @@
                             : Akonadi::Collection::root().id();
 }
 
-static const char s_contextListProperty[] = "ContextList";
-static const char s_appName[] = "Zanshin";
-
 // Should be in the serializer ideally ... but we don't link to that from here anyway.
 static QStringList extractContextUids(const Akonadi::Item &taskItem)
 {
     if (!taskItem.hasPayload<KCalCore::Todo::Ptr>())
         return {};
     auto todo = taskItem.payload<KCalCore::Todo::Ptr>();
-    const QString contexts = todo->customProperty(s_appName, s_contextListProperty);
+    const QString contexts = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     return contexts.split(',', QString::SkipEmptyParts);
 }
 
@@ -65,13 +64,13 @@
 static void removeContextFromTask(const QString &contextUid, Akonadi::Item &item)
 {
     auto todo = item.payload<KCalCore::Todo::Ptr>();
-    const QString contexts = todo->customProperty(s_appName, s_contextListProperty);
+    const QString contexts = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     QStringList contextList = contexts.split(',', QString::SkipEmptyParts);
     contextList.removeAll(contextUid);
     if (contextList.isEmpty())
-        todo->removeCustomProperty(s_appName, s_contextListProperty);
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     else
-        todo->setCustomProperty(s_appName, s_contextListProperty, contextList.join(','));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextList.join(','));
     item.setPayload<KCalCore::Todo::Ptr>(todo);
     Q_ASSERT(contextList == extractContextUids(item));
 }
@@ -83,7 +82,7 @@
         return false;
 
     auto todo = item.payload<KCalCore::Todo::Ptr>();
-    return !todo->customProperty(s_appName, "Context").isEmpty();
+    return !todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()).isEmpty();
 }
 
 AkonadiFakeData::AkonadiFakeData()
Index: tests/testlib/gentodo.cpp
===================================================================
--- tests/testlib/gentodo.cpp
+++ tests/testlib/gentodo.cpp
@@ -25,11 +25,10 @@
 
 #include <KCalCore/Todo>
 #include <QDateTime>
+#include <akonadi/akonadiserializer.h>
 
 using namespace Testlib;
-
-static const char s_contextListProperty[] = "ContextList";
-static const char s_appName[] = "Zanshin";
+using Akonadi::Serializer;
 
 GenTodo::GenTodo(const Akonadi::Item &item)
     : m_item(item)
@@ -60,30 +59,30 @@
 {
     auto todo = m_item.payload<KCalCore::Todo::Ptr>();
     if (contextUids.isEmpty())
-        todo->removeCustomProperty(s_appName, s_contextListProperty);
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList());
     else
-        todo->setCustomProperty(s_appName, s_contextListProperty, contextUids.join(','));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextUids.join(','));
     m_item.setPayload<KCalCore::Todo::Ptr>(todo);
     return *this;
 }
 
 GenTodo &GenTodo::asProject(bool value)
 {
     auto todo = m_item.payload<KCalCore::Todo::Ptr>();
     if (value)
-        todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
     else
-        todo->removeCustomProperty("Zanshin", "Project");
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject());
     return *this;
 }
 
 GenTodo &GenTodo::asContext(bool value)
 {
     auto todo = m_item.payload<KCalCore::Todo::Ptr>();
     if (value)
-        todo->setCustomProperty("Zanshin", "Context", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext(), QStringLiteral("1"));
     else
-        todo->removeCustomProperty("Zanshin", "Context");
+        todo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext());
     return *this;
 }
 
Index: tests/units/akonadi/akonadiserializertest.cpp
===================================================================
--- tests/units/akonadi/akonadiserializertest.cpp
+++ tests/units/akonadi/akonadiserializertest.cpp
@@ -35,14 +35,13 @@
 
 Q_DECLARE_METATYPE(Akonadi::Item*)
 
+using Akonadi::Serializer;
+
 static void setTodoDates(KCalCore::Todo::Ptr todo, const QDate &start, const QDate &due) {
     todo->setDtStart(QDateTime(start));
     todo->setDtDue(QDateTime(due));
 }
 
-static const char s_contextListProperty[] = "ContextList";
-static const char s_appName[] = "Zanshin";
-
 class AkonadiSerializerTest : public QObject
 {
     Q_OBJECT
@@ -533,7 +532,7 @@
         // A todo with the project flag
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         todo->setSummary(QStringLiteral("foo"));
-        todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item
         Akonadi::Item item;
@@ -647,9 +646,9 @@
         }
 
         if (updatedRunning) {
-            updatedTodo->setCustomProperty("Zanshin", "Running", "1");
+            updatedTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning(), "1");
         } else {
-            updatedTodo->removeCustomProperty("Zanshin", "Running");
+            updatedTodo->removeCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning());
         }
 
         // ... as payload of a new item
@@ -875,7 +874,7 @@
         // A todo with the project flag
         KCalCore::Todo::Ptr projectTodo(new KCalCore::Todo);
         projectTodo->setSummary(QStringLiteral("foo"));
-        projectTodo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        projectTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item
         Akonadi::Item projectItem;
@@ -1088,7 +1087,7 @@
         }
 
         QCOMPARE(todo->relatedTo(), QStringLiteral("parent-uid"));
-        QCOMPARE(todo->customProperty("Zanshin", "Running"), running ? QStringLiteral("1") : QString());
+        QCOMPARE(todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsRunning()), running ? QStringLiteral("1") : QString());
     }
 
     void shouldVerifyIfAnItemIsATaskChild_data()
@@ -1236,7 +1235,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         todo->setSummary(summary);
-        todo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
         QVERIFY(!todo->uid().isEmpty());
 
         // ... as payload of an item
@@ -1308,7 +1307,7 @@
         // A todo...
         KCalCore::Todo::Ptr originalTodo(new KCalCore::Todo);
         originalTodo->setSummary(QStringLiteral("summary"));
-        originalTodo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        originalTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item...
         Akonadi::Item originalItem(42);
@@ -1331,7 +1330,7 @@
         // ... in a new todo...
         KCalCore::Todo::Ptr updatedTodo(new KCalCore::Todo);
         updatedTodo->setSummary(updatedSummary);
-        updatedTodo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        updatedTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
         QVERIFY(!updatedTodo->uid().isEmpty());
 
         // ... as payload of a new item
@@ -1362,7 +1361,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr originalTodo(new KCalCore::Todo);
         originalTodo->setSummary(summary);
-        originalTodo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        originalTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item...
         Akonadi::Item originalItem;
@@ -1391,7 +1390,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr originalTodo(new KCalCore::Todo);
         originalTodo->setSummary(summary);
-        originalTodo->setCustomProperty("Zanshin", "Project", QStringLiteral("1"));
+        originalTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item...
         Akonadi::Item originalItem;
@@ -1471,7 +1470,7 @@
         auto todo = item.payload<KCalCore::Todo::Ptr>();
         QCOMPARE(todo->summary(), summary);
         QCOMPARE(todo->uid(), todoUid);
-        QVERIFY(!todo->customProperty("Zanshin", "Project").isEmpty());
+        QVERIFY(!todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty());
     }
 
     void shouldVerifyIfAnItemIsAProjectChild_data()
@@ -1725,7 +1724,7 @@
         if (item.hasPayload<KCalCore::Todo::Ptr>()) {
             auto todo = item.payload<KCalCore::Todo::Ptr>();
             QCOMPARE(todo->relatedTo(), QString());
-            QVERIFY(!todo->customProperty("Zanshin", "Project").isEmpty());
+            QVERIFY(!todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty());
         }
     }
 
@@ -1736,7 +1735,7 @@
         Akonadi::Item *itemWithContexts = new Akonadi::Item(15);
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         // we can cheat and not really create contexts...
-        todo->setCustomProperty(s_appName, s_contextListProperty, "one,two");
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), "one,two");
         itemWithContexts->setPayload<KCalCore::Todo::Ptr>(todo);
         QTest::newRow("with_contexts") << itemWithContexts;
 
@@ -1756,7 +1755,7 @@
 
         // THEN
         auto todo = item->payload<KCalCore::Todo::Ptr>();
-        QVERIFY(todo->customProperty(s_appName, s_contextListProperty).isEmpty());
+        QVERIFY(todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()).isEmpty());
         delete item;
     }
 
@@ -1778,7 +1777,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         todo->setSummary(name);
-        todo->setCustomProperty(s_appName, "Context", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext(), QStringLiteral("1"));
         QVERIFY(!todo->uid().isEmpty());
 
         // ... as payload of an item
@@ -1818,7 +1817,7 @@
         KCalCore::Todo::Ptr originalTodo(new KCalCore::Todo);
         originalTodo->setSummary("summary");
         if (isProject)
-            originalTodo->setCustomProperty(s_appName, "Project", QStringLiteral("1"));
+            originalTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         // ... as payload of an item...
         Akonadi::Item originalItem;
@@ -1848,7 +1847,7 @@
         // ... stored in a todo...
         KCalCore::Todo::Ptr todo(new KCalCore::Todo);
         todo->setSummary(name);
-        todo->setCustomProperty(s_appName, "Context", QStringLiteral("1"));
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext(), QStringLiteral("1"));
         QVERIFY(!todo->uid().isEmpty());
 
         // ... as payload of an item
@@ -1889,7 +1888,7 @@
         KCalCore::Todo::Ptr wrongTodo(new KCalCore::Todo);
         wrongTodo->setSummary("wrongSummary");
         if (isProject)
-            wrongTodo->setCustomProperty(s_appName, "Project", QStringLiteral("1"));
+            wrongTodo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject(), QStringLiteral("1"));
 
         Akonadi::Item wrongItem;
         wrongItem.setMimeType(QStringLiteral("application/x-vnd.akonadi.calendar.todo"));
@@ -1921,7 +1920,7 @@
         Akonadi::Item relatedItem;
         auto todo = KCalCore::Todo::Ptr::create();
         todo->setSummary("summary");
-        todo->setCustomProperty(s_appName, s_contextListProperty, contextUid);
+        todo->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextUid);
         relatedItem.setPayload<KCalCore::Todo::Ptr>(todo);
         QTest::newRow("Related item") << context << relatedItem << true;
 
@@ -2019,14 +2018,14 @@
 
         Akonadi::Item item2;
         auto todo2 = KCalCore::Todo::Ptr::create();
-        todo2->setCustomProperty(s_appName, s_contextListProperty, "another");
+        todo2->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), "another");
         item2.setPayload<KCalCore::Todo::Ptr>(todo2);
         const QString bothContexts = QStringLiteral("another,") + contextUid;
         QTest::newRow("item_with_another_context") << context << item2 << bothContexts;
 
         Akonadi::Item item3;
         auto todo3 = KCalCore::Todo::Ptr::create();
-        todo3->setCustomProperty(s_appName, s_contextListProperty, bothContexts);
+        todo3->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), bothContexts);
         item3.setPayload<KCalCore::Todo::Ptr>(todo3);
         QTest::newRow("item_with_this_context_already") << context << item3 << bothContexts;
     }
@@ -2044,7 +2043,7 @@
 
         // THEN
         KCalCore::Todo::Ptr todo = item.payload<KCalCore::Todo::Ptr>();
-        QCOMPARE(todo->customProperty(s_appName, s_contextListProperty), expectedContextList);
+        QCOMPARE(todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()), expectedContextList);
     }
 
     void shouldRemoveContextFromTask_data()
@@ -2065,20 +2064,20 @@
 
         Akonadi::Item item2;
         auto todo2 = KCalCore::Todo::Ptr::create();
-        todo2->setCustomProperty(s_appName, s_contextListProperty, "another");
+        todo2->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), "another");
         item2.setPayload<KCalCore::Todo::Ptr>(todo2);
         QTest::newRow("item_with_another_context") << context << item2 << QString("another");
 
         Akonadi::Item item3;
         auto todo3 = KCalCore::Todo::Ptr::create();
-        todo3->setCustomProperty(s_appName, s_contextListProperty, contextUid);
+        todo3->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), contextUid);
         item3.setPayload<KCalCore::Todo::Ptr>(todo3);
         QTest::newRow("item_with_this_context_already") << context << item3 << QString();
 
         Akonadi::Item item4;
         auto todo4 = KCalCore::Todo::Ptr::create();
         const QString bothContexts = QStringLiteral("another,") + contextUid;
-        todo4->setCustomProperty(s_appName, s_contextListProperty, bothContexts);
+        todo4->setCustomProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList(), bothContexts);
         item4.setPayload<KCalCore::Todo::Ptr>(todo4);
         QTest::newRow("item_with_two_contexts") << context << item4 << QString("another");
     }
@@ -2096,7 +2095,7 @@
 
         // THEN
         KCalCore::Todo::Ptr todo = item.payload<KCalCore::Todo::Ptr>();
-        QCOMPARE(todo->customProperty(s_appName, s_contextListProperty), expectedContextList);
+        QCOMPARE(todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()), expectedContextList);
     }
 
     // Investigation into how to differentiate all-day events from events with time,
Index: tests/units/akonadi/testenv/data/testdata.xml
===================================================================
--- tests/units/akonadi/testenv/data/testdata.xml
+++ tests/units/akonadi/testenv/data/testdata.xml
@@ -70,7 +70,7 @@
 UID:f1a30fc7-d941-4c81-a083-7c1e9657ae24&#xd;
 LAST-MODIFIED:20120322T164413Z&#xd;
 SUMMARY: Prepare the talk on TDD&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 PERCENT-COMPLETE:0&#xd;
 END:VTODO&#xd;
 
@@ -268,7 +268,7 @@
 BEGIN:VTODO&#xd;
 CREATED:20190317T162551Z&#xd;
 UID:errands-context&#xd;
-X-KDE-Zanshin-Context:1&#xd;
+X-KDE-ZANSHIN-CONTEXT:1&#xd;
 LAST-MODIFIED:20140317T162551Z&#xd;
 SUMMARY:Errands&#xd;
 END:VTODO&#xd;
@@ -283,7 +283,7 @@
 BEGIN:VTODO&#xd;
 CREATED:20190317T162551Z&#xd;
 UID:online-context&#xd;
-X-KDE-Zanshin-Context:1&#xd;
+X-KDE-ZANSHIN-CONTEXT:1&#xd;
 LAST-MODIFIED:20140317T162551Z&#xd;
 SUMMARY:Online&#xd;
 END:VTODO&#xd;
Index: tests/units/migrator/testenv/data/testdata.xml
===================================================================
--- tests/units/migrator/testenv/data/testdata.xml
+++ tests/units/migrator/testenv/data/testdata.xml
@@ -49,7 +49,7 @@
 CREATED:20111214T031148Z&#xd;
 UID:project-with-comment-and-property&#xd;
 COMMENT:X-Zanshin-Project&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 LAST-MODIFIED:20111214T031148Z&#xd;
 SUMMARY:Buy apples&#xd;
 PERCENT-COMPLETE:0&#xd;
@@ -69,7 +69,7 @@
 DTSTAMP:20140317T162551Z&#xd;
 CREATED:20140317T162551Z&#xd;
 UID:new-project-with-property&#xd;
-X-KDE-Zanshin-Project:1&#xd;
+X-KDE-ZANSHIN-PROJECT:1&#xd;
 LAST-MODIFIED:20140317T162551Z&#xd;
 SUMMARY:Buy pears&#xd;
 DUE;VALUE=DATE:20140324&#xd;
Index: tests/units/migrator/zanshincontextitemsmigrationtest.cpp
===================================================================
--- tests/units/migrator/zanshincontextitemsmigrationtest.cpp
+++ tests/units/migrator/zanshincontextitemsmigrationtest.cpp
@@ -45,6 +45,8 @@
 
 #include <QProcess>
 
+using Akonadi::Serializer;
+
 class ZanshinContextItemsMigrationTest : public QObject
 {
     Q_OBJECT
@@ -194,7 +196,7 @@
             //qDebug() << item.id() << it.key();
             auto todo = item.payload<KCalCore::Todo::Ptr>();
             QVERIFY(todo);
-            const auto contextUids = todo->customProperty("Zanshin", "ContextList").split(',', QString::SkipEmptyParts);
+            const auto contextUids = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()).split(',', QString::SkipEmptyParts);
             QStringList contextNames;
             std::transform(contextUids.cbegin(), contextUids.cend(), std::back_inserter(contextNames), [this](const QString &uid) { return m_contextTodos.value(uid); });
             contextNames.sort();
Index: tests/units/testlib/akonadifakedataxmlloadertest.cpp
===================================================================
--- tests/units/testlib/akonadifakedataxmlloadertest.cpp
+++ tests/units/testlib/akonadifakedataxmlloadertest.cpp
@@ -23,11 +23,14 @@
 
 #include "testlib/akonadifakedata.h"
 #include "testlib/akonadifakedataxmlloader.h"
+#include <akonadi/akonadiserializer.h>
 
 #include <KCalCore/Todo>
 
 #include <testlib/qtest_zanshin.h>
 
+using Akonadi::Serializer;
+
 class AkonadiFakeDataXmlLoaderTest : public QObject
 {
     Q_OBJECT
@@ -84,7 +87,7 @@
         const auto contextAsTodo = firstContext.payload<KCalCore::Todo::Ptr>();
         QCOMPARE(contextAsTodo->uid(), "online-context");
         QCOMPARE(contextAsTodo->summary(), "Online");
-        QCOMPARE(contextAsTodo->customProperty("Zanshin", "Context"), "1");
+        QCOMPARE(contextAsTodo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()), "1");
     }
 };
 
Index: tests/units/testlib/gentodotest.cpp
===================================================================
--- tests/units/testlib/gentodotest.cpp
+++ tests/units/testlib/gentodotest.cpp
@@ -26,8 +26,10 @@
 #include <KCalCore/Todo>
 
 #include <testlib/qtest_zanshin.h>
+#include <akonadi/akonadiserializer.h>
 
 using namespace Testlib;
+using Akonadi::Serializer;
 
 class GenTodoTest : public QObject
 {
@@ -73,7 +75,7 @@
 
         // THEN
         auto todo = item.payload<KCalCore::Todo::Ptr>();
-        QStringList contextUids = todo->customProperty("Zanshin", "ContextList").split(',');
+        QStringList contextUids = todo->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyContextList()).split(',');
         QCOMPARE(contextUids.size(), 3);
         QCOMPARE(contextUids.at(0), "42");
         QCOMPARE(contextUids.at(1), "43");
@@ -86,28 +88,28 @@
         Akonadi::Item item = GenTodo().asProject();
 
         // THEN
-        QVERIFY(!item.payload<KCalCore::Todo::Ptr>()->customProperty("Zanshin", "Project").isEmpty());
+        QVERIFY(!item.payload<KCalCore::Todo::Ptr>()->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty());
 
         // WHEN
         item = GenTodo(item).asProject(false);
 
         // THEN
-        QVERIFY(item.payload<KCalCore::Todo::Ptr>()->customProperty("Zanshin", "Project").isEmpty());
+        QVERIFY(item.payload<KCalCore::Todo::Ptr>()->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsProject()).isEmpty());
     }
 
     void shouldAllowToSetContextType()
     {
         // GIVEN
         Akonadi::Item item = GenTodo().asContext();
 
         // THEN
-        QVERIFY(!item.payload<KCalCore::Todo::Ptr>()->customProperty("Zanshin", "Context").isEmpty());
+        QVERIFY(!item.payload<KCalCore::Todo::Ptr>()->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()).isEmpty());
 
         // WHEN
         item = GenTodo(item).asContext(false);
 
         // THEN
-        QVERIFY(item.payload<KCalCore::Todo::Ptr>()->customProperty("Zanshin", "Context").isEmpty());
+        QVERIFY(item.payload<KCalCore::Todo::Ptr>()->customProperty(Serializer::customPropertyAppName(), Serializer::customPropertyIsContext()).isEmpty());
     }
 
     void shouldAllowToSetUid()