diff --git a/src/attachmenthandler.cpp b/src/attachmenthandler.cpp
index c4bc08ab95618f6b4986e897ab99741ccdede45d..2a5593a1120ffa6053696a22abb076c211b6a245 100644
--- a/src/attachmenthandler.cpp
+++ b/src/attachmenthandler.cpp
@@ -143,7 +143,7 @@ Attachment::Ptr AttachmentHandler::find(const QString &attachmentName,
     return find(attachmentName, incidence);
 }
 
-static QTemporaryFile *s_tempFile = 0;
+static QTemporaryFile *s_tempFile = Q_NULLPTR;
 
 static QUrl tempFileForAttachment(const Attachment::Ptr &attachment)
 {
@@ -165,7 +165,7 @@ static QUrl tempFileForAttachment(const Attachment::Ptr &attachment)
     if (tf.size() != attachment->size()) {
         //whoops. failed to write the entire attachment. return an invalid URL.
         delete s_tempFile;
-        s_tempFile = 0;
+        s_tempFile = Q_NULLPTR;
         return url;
     }
 
@@ -186,7 +186,7 @@ bool AttachmentHandler::view(const Attachment::Ptr &attachment)
         // put the attachment in a temporary file and launch it
         QUrl tempUrl = tempFileForAttachment(attachment);
         if (tempUrl.isValid()) {
-            stat = KRun::runUrl(tempUrl, attachment->mimeType(), 0, true);
+            stat = KRun::runUrl(tempUrl, attachment->mimeType(), Q_NULLPTR, true);
         } else {
             stat = false;
             KMessageBox::error(
@@ -194,7 +194,7 @@ bool AttachmentHandler::view(const Attachment::Ptr &attachment)
                 i18n("Unable to create a temporary file for the attachment."));
         }
         delete s_tempFile;
-        s_tempFile = 0;
+        s_tempFile = Q_NULLPTR;
     }
     return stat;
 }
@@ -257,7 +257,7 @@ bool AttachmentHandler::saveAs(const Attachment::Ptr &attachment)
                 i18n("Unable to create a temporary file for the attachment."));
         }
         delete s_tempFile;
-        s_tempFile = 0;
+        s_tempFile = Q_NULLPTR;
     }
     return stat;
 }
diff --git a/src/calendarutils.cpp b/src/calendarutils.cpp
index fb1e0376ad0c352f0a001f0be51892569c3c0794..18fdc059878e29654e32fe5969648c2941c36d18 100644
--- a/src/calendarutils.cpp
+++ b/src/calendarutils.cpp
@@ -152,7 +152,7 @@ bool CalendarUtilsPrivate::purgeCompletedSubTodos(const KCalCore::Todo::Ptr &tod
 
     if (deleteThisTodo) {
         if (todo->isCompleted()) {
-            if (!mChanger->deleteIncidence(mCalendar->item(todo), 0)) {
+            if (!mChanger->deleteIncidence(mCalendar->item(todo), Q_NULLPTR)) {
                 allPurged = false;
             }
         } else {
@@ -259,7 +259,7 @@ void CalendarUtils::purgeCompletedTodos()
 //  endMultiModify();
     if (!allDeleted) {
         KMessageBox::information(
-            0,
+            Q_NULLPTR,
             i18nc("@info",
                   "Unable to purge to-dos with uncompleted children."),
             i18nc("@title:window", "Delete To-do"),
diff --git a/src/incidenceattachmentmodel.cpp b/src/incidenceattachmentmodel.cpp
index 055ac13eef0468264855bb2e742033039dec930a..89be463e98b7e5e6f910ca33db23abdf10f3c431 100644
--- a/src/incidenceattachmentmodel.cpp
+++ b/src/incidenceattachmentmodel.cpp
@@ -36,7 +36,7 @@ class IncidenceAttachmentModelPrivate
     IncidenceAttachmentModelPrivate(IncidenceAttachmentModel *qq,
                                     const QPersistentModelIndex &modelIndex,
                                     const Akonadi::Item &item = Akonadi::Item())
-        : q_ptr(qq), m_modelIndex(modelIndex), m_item(item), m_monitor(0)
+        : q_ptr(qq), m_modelIndex(modelIndex), m_item(item), m_monitor(Q_NULLPTR)
     {
         if (modelIndex.isValid()) {
             QObject::connect(modelIndex.model(), SIGNAL(dataChanged(QModelIndex,QModelIndex)),
diff --git a/src/utils.cpp b/src/utils.cpp
index 90bf4b4c7990227065f13bd22a3e2ea4447cd9a3..d74839cd14f2b8e03cad157071d87e6aa94aa501 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -196,7 +196,7 @@ QMimeData *CalendarSupport::createMimeData(const Akonadi::Item::List &items,
         const KDateTime::Spec &timeSpec)
 {
     if (items.isEmpty()) {
-        return 0;
+        return Q_NULLPTR;
     }
 
     KCalCore::MemoryCalendar::Ptr cal(new KCalCore::MemoryCalendar(timeSpec));
@@ -215,7 +215,7 @@ QMimeData *CalendarSupport::createMimeData(const Akonadi::Item::List &items,
     }
 
     if (incidencesFound == 0) {
-        return 0;
+        return Q_NULLPTR;
     }
 
     std::unique_ptr<QMimeData> mimeData(new QMimeData);