diff --git a/autotests/kactionmenutransporttest.h b/autotests/kactionmenutransporttest.h
index cac0d46d7..2ea0e05d5 100644
--- a/autotests/kactionmenutransporttest.h
+++ b/autotests/kactionmenutransporttest.h
@@ -24,7 +24,7 @@ class KActionMenuTransportTest : public QObject
 {
     Q_OBJECT
 public:
-    explicit KActionMenuTransportTest(QObject *parent = 0);
+    explicit KActionMenuTransportTest(QObject *parent = Q_NULLPTR);
     ~KActionMenuTransportTest();
 private Q_SLOTS:
     void shouldHaveDefaultValue();
diff --git a/mailmerge/autotests/mailmergejobtest.h b/mailmerge/autotests/mailmergejobtest.h
index 5e2989544..7d258848e 100644
--- a/mailmerge/autotests/mailmergejobtest.h
+++ b/mailmerge/autotests/mailmergejobtest.h
@@ -24,7 +24,7 @@ class MailMergeJobTest : public QObject
 {
     Q_OBJECT
 public:
-    explicit MailMergeJobTest(QObject *parent = 0);
+    explicit MailMergeJobTest(QObject *parent = Q_NULLPTR);
     ~MailMergeJobTest();
 };
 
diff --git a/mailmerge/job/mailmergejob.h b/mailmerge/job/mailmergejob.h
index 6b7a0c922..9a34348d4 100644
--- a/mailmerge/job/mailmergejob.h
+++ b/mailmerge/job/mailmergejob.h
@@ -25,7 +25,7 @@ class MailMergeJob : public QObject
 {
     Q_OBJECT
 public:
-    explicit MailMergeJob(QObject *parent = 0);
+    explicit MailMergeJob(QObject *parent = Q_NULLPTR);
     ~MailMergeJob();
 };
 }
diff --git a/widgets/kactionmenutransport.h b/widgets/kactionmenutransport.h
index a38730f21..98f85450b 100644
--- a/widgets/kactionmenutransport.h
+++ b/widgets/kactionmenutransport.h
@@ -28,7 +28,7 @@ class KActionMenuTransport : public KActionMenu
 {
     Q_OBJECT
 public:
-    explicit KActionMenuTransport(QObject *parent = 0);
+    explicit KActionMenuTransport(QObject *parent = Q_NULLPTR);
     ~KActionMenuTransport();
 
 Q_SIGNALS: