diff --git a/src/autotests/displaymessageformatactionmenutest.cpp b/src/autotests/displaymessageformatactionmenutest.cpp
index 535834bc1..5b1ba000a 100644
--- a/src/autotests/displaymessageformatactionmenutest.cpp
+++ b/src/autotests/displaymessageformatactionmenutest.cpp
@@ -47,7 +47,7 @@ void DisplayMessageFormatActionMenuTest::shouldEmitSignalWhenClickOnSubMenu()
 {
     DisplayMessageFormatActionMenu menu;
     KToggleAction *prefereHtml = menu.findChild<KToggleAction *>(QStringLiteral("prefer-html-action"));
-    QSignalSpy spy(&menu, SIGNAL(changeDisplayMessageFormat(MessageViewer::Viewer::DisplayFormatMessage)));
+    QSignalSpy spy(&menu, &DisplayMessageFormatActionMenu::changeDisplayMessageFormat);
     prefereHtml->trigger();
     QCOMPARE(spy.count(), 1);
     QCOMPARE(spy.at(0).at(0).value<MessageViewer::Viewer::DisplayFormatMessage>(), MessageViewer::Viewer::Html);
@@ -69,7 +69,7 @@ void DisplayMessageFormatActionMenuTest::shouldSelectItemWhenChangeFormat()
 void DisplayMessageFormatActionMenuTest::shouldDontEmitSignalWhenChangeFormat()
 {
     DisplayMessageFormatActionMenu menu;
-    QSignalSpy spy(&menu, SIGNAL(changeDisplayMessageFormat(MessageViewer::Viewer::DisplayFormatMessage)));
+    QSignalSpy spy(&menu, &DisplayMessageFormatActionMenu::changeDisplayMessageFormat);
     menu.setDisplayMessageFormat(MessageViewer::Viewer::Text);
     QCOMPARE(spy.count(), 0);
 }
diff --git a/src/autotests/statusbarlabeltoggledstatetest.cpp b/src/autotests/statusbarlabeltoggledstatetest.cpp
index 8b4926ea0..b8e210276 100644
--- a/src/autotests/statusbarlabeltoggledstatetest.cpp
+++ b/src/autotests/statusbarlabeltoggledstatetest.cpp
@@ -56,7 +56,7 @@ void StatusBarLabelToggledStateTest::shouldEmitSignalWhenChangeState()
 {
     StatusBarLabelToggledState widget;
     widget.setStateString(QStringLiteral("toggle"), QStringLiteral("untoggle"));
-    QSignalSpy spy(&widget, SIGNAL(toggleModeChanged(bool)));
+    QSignalSpy spy(&widget, &StatusBarLabelToggledState::toggleModeChanged);
     widget.setToggleMode(true);
     QCOMPARE(spy.count(), 1);
 
@@ -68,7 +68,7 @@ void StatusBarLabelToggledStateTest::shouldNotEmitSignalWhenWeDontChangeState()
 {
     StatusBarLabelToggledState widget;
     widget.setStateString(QStringLiteral("toggle"), QStringLiteral("untoggle"));
-    QSignalSpy spy(&widget, SIGNAL(toggleModeChanged(bool)));
+    QSignalSpy spy(&widget, &StatusBarLabelToggledState::toggleModeChanged);
     widget.setToggleMode(false);
     QCOMPARE(spy.count(), 0);
 
@@ -83,7 +83,7 @@ void StatusBarLabelToggledStateTest::shouldEmitSignalWhenClickOnLabel()
 {
     StatusBarLabelToggledState widget;
     widget.setStateString(QStringLiteral("toggle"), QStringLiteral("untoggle"));
-    QSignalSpy spy(&widget, SIGNAL(toggleModeChanged(bool)));
+    QSignalSpy spy(&widget, &StatusBarLabelToggledState::toggleModeChanged);
     widget.show();
     QVERIFY(QTest::qWaitForWindowExposed(&widget));
     QTest::mouseClick(&widget, Qt::LeftButton);
diff --git a/src/editor/potentialphishingemail/autotests/potentialphishingemailjobtest.cpp b/src/editor/potentialphishingemail/autotests/potentialphishingemailjobtest.cpp
index cefe75d98..259018400 100644
--- a/src/editor/potentialphishingemail/autotests/potentialphishingemailjobtest.cpp
+++ b/src/editor/potentialphishingemail/autotests/potentialphishingemailjobtest.cpp
@@ -86,7 +86,7 @@ void PotentialPhishingEmailJobTest::shouldReturnPotentialPhishingEmails()
 void PotentialPhishingEmailJobTest::shouldEmitSignal()
 {
     PotentialPhishingEmailJob *job = new PotentialPhishingEmailJob;
-    QSignalSpy spy(job, SIGNAL(potentialPhishingEmailsFound(QStringList)));
+    QSignalSpy spy(job, &PotentialPhishingEmailJob::potentialPhishingEmailsFound);
     job->setPotentialPhishingEmails((QStringList() << QStringLiteral("\"bla@kde.org\" <foo@kde.org>")));
     job->start();
     QCOMPARE(spy.count(), 1);
diff --git a/src/kmmainwidget.cpp b/src/kmmainwidget.cpp
index 1dc043f63..69e80f111 100644
--- a/src/kmmainwidget.cpp
+++ b/src/kmmainwidget.cpp
@@ -204,7 +204,7 @@ using MessageViewer::AttachmentStrategy;
 Q_GLOBAL_STATIC(KMMainWidget::PtrList, theMainWidgetList)
 
 //-----------------------------------------------------------------------------
-KMMainWidget::KMMainWidget(QWidget *parent, KXMLGUIClient *aGUIClient, KActionCollection *actionCollection, KSharedConfig::Ptr config)
+KMMainWidget::KMMainWidget(QWidget *parent, KXMLGUIClient *aGUIClient, KActionCollection *actionCollection, const KSharedConfig::Ptr &config)
     : QWidget(parent)
     , mManageShowCollectionProperties(new ManageShowCollectionProperties(this, this))
 {
diff --git a/src/kmmainwidget.h b/src/kmmainwidget.h
index b7f8bb3fa..b044c67a3 100644
--- a/src/kmmainwidget.h
+++ b/src/kmmainwidget.h
@@ -97,7 +97,7 @@ class KMAIL_EXPORT KMMainWidget : public QWidget
 public:
     typedef QList<KMMainWidget *> PtrList;
 
-    KMMainWidget(QWidget *parent, KXMLGUIClient *aGUIClient, KActionCollection *actionCollection, KSharedConfig::Ptr config = KMKernel::self()->config());
+    KMMainWidget(QWidget *parent, KXMLGUIClient *aGUIClient, KActionCollection *actionCollection, const KSharedConfig::Ptr &config = KMKernel::self()->config());
     ~KMMainWidget() override;
     void destruct();