diff --git a/autotests/documenttest.cpp b/autotests/documenttest.cpp
--- a/autotests/documenttest.cpp
+++ b/autotests/documenttest.cpp
@@ -73,7 +73,7 @@
 // the document without migrating and that it does get wiped out after migrating
 void DocumentTest::testDocdataMigration()
 {
-    Okular::SettingsCore::instance( "documenttest" );
+    Okular::SettingsCore::instance( QStringLiteral("documenttest") );
 
     const QUrl testFileUrl = QUrl::fromLocalFile(KDESRCDIR "data/file1.pdf");
     const QString testFilePath = testFileUrl.toLocalFile();
@@ -106,7 +106,7 @@
     QCOMPARE( m_document->isDocdataMigrationNeeded(), true );
 
     // Do the migration
-    QTemporaryFile migratedSaveFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+    QTemporaryFile migratedSaveFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
     QVERIFY( migratedSaveFile.open() );
     migratedSaveFile.close();
     QVERIFY( m_document->saveChanges( migratedSaveFile.fileName() ) );
diff --git a/autotests/mainshelltest.cpp b/autotests/mainshelltest.cpp
--- a/autotests/mainshelltest.cpp
+++ b/autotests/mainshelltest.cpp
@@ -203,7 +203,7 @@
     QTest::newRow("two files sequence with tabs") << file1 << QString() << true << tocReload << 0u << false << false << false << 0u << false << false << QString();
     QTest::newRow("open file page number") << contentsEpub << optionsPage2 << false << QString() << 1u << false << false << false << 0u << false << false << QString();
     QTest::newRow("open file page number and presentation") << contentsEpub << optionsPage2Presentation << false << QString() << 1u << true << false << false << 0u << false << false << QString();
-    QTest::newRow("open file find") << file1 << optionsFind << false << QString() << 0u << false << false << false << 0u << false << false << QString("si:next-testing parameters!"); 
+    QTest::newRow("open file find") << file1 << optionsFind << false << QString() << 0u << false << false << false << 0u << false << false << QStringLiteral("si:next-testing parameters!"); 
     QTest::newRow("open file print") << file1 << optionsPrint << false << QString() << 0u << false << true << false << 0u << false << false << QString();
     QTest::newRow("open two files unique") << file1 << optionsUnique << false << tocReload << 0u << false << false << true << 0u << false << false << QString();
     QTest::newRow("open two files unique tabs") << file1 << optionsUnique << true << tocReload << 0u << false << false << true << 0u << false << false << QString();
diff --git a/autotests/parttest.cpp b/autotests/parttest.cpp
--- a/autotests/parttest.cpp
+++ b/autotests/parttest.cpp
@@ -215,7 +215,7 @@
     QProcess process;
     process.setWorkingDirectory(workDir.path());
 
-    const QString pdflatexPath(QStandardPaths::findExecutable("pdflatex"));
+    const QString pdflatexPath(QStandardPaths::findExecutable(QStringLiteral("pdflatex")));
     if (pdflatexPath.isEmpty()) {
         QFAIL("pdflatex executable not found, but needed for the test. Try installing the respective TeXLive packages.");
     }
@@ -254,8 +254,8 @@
 {
     QTest::addColumn<QString>("dir");
 
-    QTest::newRow("non-utf8") << QString::fromUtf8("synctextest");
-    QTest::newRow("utf8")     << QString::fromUtf8("ßðđđŋßðđŋ");
+    QTest::newRow("non-utf8") << QStringLiteral("synctextest");
+    QTest::newRow("utf8")     << QStringLiteral("ßðđđŋßðđŋ");
 }
 
 void PartTest::testGeneratorPreferences()
@@ -390,8 +390,8 @@
     QVERIFY(QMetaObject::invokeMethod(part.m_pageView, "slotSetMouseTextSelect"));
 
     // overwrite urlHandler for 'mailto' urls
-    QDesktopServices::setUrlHandler("mailto", this, "urlHandler");
-    QSignalSpy openUrlSignalSpy(this, SIGNAL(urlHandler(QUrl)));
+    QDesktopServices::setUrlHandler(QStringLiteral("mailto"), this, "urlHandler");
+    QSignalSpy openUrlSignalSpy(this, &PartTest::urlHandler);
 
     // click on url
     QTest::mouseMove(part.m_pageView->viewport(), QPoint(width * 0.250, height * 0.127));
@@ -488,8 +488,8 @@
     simulateMouseSelection(mouseStartX, mouseY, mouseEndX, mouseY, part.m_pageView->viewport());
 
     // overwrite urlHandler for 'mailto' urls
-    QDesktopServices::setUrlHandler("mailto", this, "urlHandler");
-    QSignalSpy openUrlSignalSpy(this, SIGNAL(urlHandler(QUrl)));
+    QDesktopServices::setUrlHandler(QStringLiteral("mailto"), this, "urlHandler");
+    QSignalSpy openUrlSignalSpy(this, &PartTest::urlHandler);
 
     // click on url
     const double mouseClickX = width * 0.2997;
@@ -540,20 +540,20 @@
     bool menuClosed = false;
     QTimer::singleShot(2000, [view, &menuClosed]() {
         // check if popup menu is active and visible
-        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>("PopupMenu"));
+        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>(QStringLiteral("PopupMenu")));
         QVERIFY(menu);
         QVERIFY(menu->isVisible());
 
         // check if the menu contains go-to link action
-        QAction *goToAction = qobject_cast<QAction*>(menu->findChild<QAction*>("GoToAction"));
+        QAction *goToAction = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("GoToAction")));
         QVERIFY(goToAction);
 
         // check if the "follow this link" action is not visible
-        QAction *processLinkAction = qobject_cast<QAction*>(menu->findChild<QAction*>("ProcessLinkAction"));
+        QAction *processLinkAction = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("ProcessLinkAction")));
         QVERIFY(!processLinkAction);
 
         // check if the "copy link address" action is not visible
-        QAction *copyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>("CopyLinkLocationAction"));
+        QAction *copyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("CopyLinkLocationAction")));
         QVERIFY(!copyLinkLocation);
 
         // close menu to continue test
@@ -609,16 +609,16 @@
     bool menuClosed = false;
     QTimer::singleShot(2000, [view, &menuClosed]() {
         // check if popup menu is active and visible
-        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>("PopupMenu"));
+        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>(QStringLiteral("PopupMenu")));
         QVERIFY(menu);
         QVERIFY(menu->isVisible());
 
         // check if the menu contains "follow this link" action
-        QAction *processLinkAction = qobject_cast<QAction*>(menu->findChild<QAction*>("ProcessLinkAction"));
+        QAction *processLinkAction = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("ProcessLinkAction")));
         QVERIFY(processLinkAction);
 
         // check if the menu contains "copy link address" action
-        QAction *copyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>("CopyLinkLocationAction"));
+        QAction *copyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("CopyLinkLocationAction")));
         QVERIFY(copyLinkLocation);
 
         // close menu to continue test
@@ -666,16 +666,16 @@
     bool menuClosed = false;
     QTimer::singleShot(2000, [view, &menuClosed]() {
         // check if popup menu is active and visible
-        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>("PopupMenu"));
+        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>(QStringLiteral("PopupMenu")));
         QVERIFY(menu);
         QVERIFY(menu->isVisible());
 
         // check if the menu contains "Follow this link" action
-        QAction *processLink = qobject_cast<QAction*>(menu->findChild<QAction*>("ProcessLinkAction"));
+        QAction *processLink = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("ProcessLinkAction")));
         QVERIFY(processLink);
 
         // chek if the menu contains  "Copy Link Address" action
-        QAction *actCopyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>("CopyLinkLocationAction"));
+        QAction *actCopyLinkLocation = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("CopyLinkLocationAction")));
         QVERIFY(actCopyLinkLocation);
 
         // close menu to continue test
@@ -772,12 +772,12 @@
         QApplication::clipboard()->clear();
 
         // check if popup menu is active and visible
-        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>("PopupMenu"));
+        QMenu *menu = qobject_cast<QMenu*>(view->findChild<QMenu*>(QStringLiteral("PopupMenu")));
         QVERIFY(menu);
         QVERIFY(menu->isVisible());
 
         // check if the copy selected text to clipboard is present
-        QAction *copyAct = qobject_cast<QAction*>(menu->findChild<QAction*>("CopyTextToClipboard"));
+        QAction *copyAct = qobject_cast<QAction*>(menu->findChild<QAction*>(QStringLiteral("CopyTextToClipboard")));
         QVERIFY(copyAct);
 
         menu->close();
@@ -820,7 +820,7 @@
 
     QString saveFilePath;
     {
-        QTemporaryFile saveFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+        QTemporaryFile saveFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
         saveFile.open();
         saveFilePath = saveFile.fileName();
         // QTemporaryFile is destroyed and the file it created is gone, this is a TOCTOU but who cares
@@ -839,12 +839,12 @@
     Okular::Part part(nullptr, nullptr, QVariantList());
     part.openDocument( KDESRCDIR "data/file1.pdf" );
 
-    QTemporaryFile newFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+    QTemporaryFile newFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
     newFile.open();
 
     QString linkFilePath;
     {
-        QTemporaryFile linkFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+        QTemporaryFile linkFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
         linkFile.open();
         linkFilePath = linkFile.fileName();
         // QTemporaryFile is destroyed and the file it created is gone, this is a TOCTOU but who cares
@@ -869,7 +869,7 @@
 
     QString newFilePath;
     {
-        QTemporaryFile newFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+        QTemporaryFile newFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
         newFile.open();
         newFilePath = newFile.fileName();
         // QTemporaryFile is destroyed and the file it created is gone, this is a TOCTOU but who cares
@@ -879,7 +879,7 @@
 
     QString linkFilePath;
     {
-        QTemporaryFile linkFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+        QTemporaryFile linkFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
         linkFile.open();
         linkFilePath = linkFile.fileName();
         // QTemporaryFile is destroyed and the file it created is gone, this is a TOCTOU but who cares
@@ -909,9 +909,9 @@
     QScopedPointer<CloseDialogHelper> closeDialogHelper;
 
     QString annotName;
-    QTemporaryFile archiveSave( QString( "%1/okrXXXXXX.okular" ).arg( QDir::tempPath() ) );
-    QTemporaryFile nativeDirectSave( QString( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
-    QTemporaryFile nativeFromArchiveFile( QString( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
+    QTemporaryFile archiveSave( QStringLiteral( "%1/okrXXXXXX.okular" ).arg( QDir::tempPath() ) );
+    QTemporaryFile nativeDirectSave( QStringLiteral( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
+    QTemporaryFile nativeFromArchiveFile( QStringLiteral( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
     QVERIFY( archiveSave.open() );
     archiveSave.close();
     QVERIFY( nativeDirectSave.open() );
@@ -929,7 +929,7 @@
 
         Okular::Annotation *annot = new Okular::TextAnnotation();
         annot->setBoundingRectangle( Okular::NormalizedRect( 0.1, 0.1, 0.15, 0.15 ) );
-        annot->setContents( "annot contents" );
+        annot->setContents( QStringLiteral("annot contents") );
         part.m_document->addPageAnnotation( 0, annot );
         annotName = annot->uniqueName();
 
@@ -1064,10 +1064,10 @@
     // when saving to a file format not supporting those. However, this button is only sensible
     // and available for "Save As", but not for "Save". By alternately saving to saveFile1 and
     // saveFile2 we always force "Save As", so closeDialogHelper keeps working.
-    QTemporaryFile saveFile1( QString( "%1/okrXXXXXX_1.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
+    QTemporaryFile saveFile1( QStringLiteral( "%1/okrXXXXXX_1.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
     QVERIFY( saveFile1.open() );
     saveFile1.close();
-    QTemporaryFile saveFile2( QString( "%1/okrXXXXXX_2.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
+    QTemporaryFile saveFile2( QStringLiteral( "%1/okrXXXXXX_2.%2" ).arg( QDir::tempPath() ).arg ( extension ) );
     QVERIFY( saveFile2.open() );
     saveFile2.close();
 
@@ -1078,7 +1078,7 @@
 
     Okular::Annotation *annot = new Okular::TextAnnotation();
     annot->setBoundingRectangle( Okular::NormalizedRect( 0.1, 0.1, 0.15, 0.15 ) );
-    annot->setContents( "annot contents" );
+    annot->setContents( QStringLiteral("annot contents") );
     part.m_document->addPageAnnotation( 0, annot );
     QString annotName = annot->uniqueName();
 
@@ -1250,7 +1250,7 @@
 
     const Part::SaveAsFlag saveFlags = saveToArchive ? Part::SaveAsOkularArchive : Part::NoSaveAsFlags;
 
-    QTemporaryFile saveFile( QString( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath(), extension ) );
+    QTemporaryFile saveFile( QStringLiteral( "%1/okrXXXXXX.%2" ).arg( QDir::tempPath(), extension ) );
     QVERIFY( saveFile.open() );
     saveFile.close();
 
@@ -1263,7 +1263,7 @@
         {
             QCOMPARE( ff->type(), FormField::FormText );
             FormFieldText *fft = static_cast<FormFieldText *>( ff );
-            part.m_document->editFormText( 0, fft, "BlaBla", 6, 0, 0 );
+            part.m_document->editFormText( 0, fft, QStringLiteral("BlaBla"), 6, 0, 0 );
         }
         else if ( ff->id() == 65538 )
         {
@@ -1284,7 +1284,7 @@
             QCOMPARE( ff->type(), FormField::FormChoice );
             FormFieldChoice *ffc = static_cast<FormFieldChoice *>( ff );
             QCOMPARE( ffc->choiceType(), FormFieldChoice::ComboBox );
-            part.m_document->editFormCombo( 0, ffc, "combo2", 3, 0, 0);
+            part.m_document->editFormCombo( 0, ffc, QStringLiteral("combo2"), 3, 0, 0);
         }
     }
 
@@ -1484,7 +1484,7 @@
     btnStates << true << true;
     part.m_document->editFormButtons( 0, btns, btnStates );
 
-    QTemporaryFile saveFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+    QTemporaryFile saveFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
     QVERIFY( saveFile.open() );
     saveFile.close();
 
@@ -1525,7 +1525,7 @@
     part.widget()->show();
     QVERIFY(QTest::qWaitForWindowExposed(part.widget()));
 
-    part.widget()->findChild<QTextEdit*>()->setText("HOLA");
+    part.widget()->findChild<QTextEdit*>()->setText(QStringLiteral("HOLA"));
     part.actionCollection()->action(QStringLiteral("view_toggle_forms"))->trigger();
 }
 
@@ -1574,16 +1574,16 @@
     QTest::mouseDClick(part.m_pageView->viewport(), Qt::LeftButton, Qt::NoModifier, QPoint(width * annot1pt.x, height * annot1pt.y));
     QTRY_COMPARE( part.m_pageView->findChildren<QFrame *>("AnnotWindow").size(), 1 );
     // Verify that the window is visible
-    QFrame* win1 = part.m_pageView->findChild<QFrame *>("AnnotWindow");
+    QFrame* win1 = part.m_pageView->findChild<QFrame *>(QStringLiteral("AnnotWindow"));
     QVERIFY( !win1->visibleRegion().isEmpty() );
 
     // Double click the second annotation to open its window (move mouse for visual feedback)
     const NormalizedPoint annot2pt = annot2->boundingRectangle().center();
     QTest::mouseMove(part.m_pageView->viewport(), QPoint(width * annot2pt.x, height * annot2pt.y));
     QTest::mouseDClick(part.m_pageView->viewport(), Qt::LeftButton, Qt::NoModifier, QPoint(width * annot2pt.x, height * annot2pt.y));
     QTRY_COMPARE( part.m_pageView->findChildren<QFrame *>("AnnotWindow").size(), 2 );
     // Verify that the first window is hidden covered by the second, which is visible
-    QList<QFrame *> lstWin = part.m_pageView->findChildren<QFrame *>("AnnotWindow");
+    QList<QFrame *> lstWin = part.m_pageView->findChildren<QFrame *>(QStringLiteral("AnnotWindow"));
     QFrame * win2;
     if (lstWin[0] == win1) {
         win2 = lstWin[1];
@@ -1808,8 +1808,8 @@
     qunsetenv("QT_MESSAGE_PATTERN");
 
     QApplication app( argc, argv );
-    app.setApplicationName(QLatin1String("okularparttest"));
-    app.setOrganizationDomain(QLatin1String("kde.org"));
+    app.setApplicationName(QStringLiteral("okularparttest"));
+    app.setOrganizationDomain(QStringLiteral("kde.org"));
     app.setQuitOnLastWindowClosed(false);
 
     qRegisterMetaType<QUrl>(); /*as done by kapplication*/
diff --git a/autotests/searchtest.cpp b/autotests/searchtest.cpp
--- a/autotests/searchtest.cpp
+++ b/autotests/searchtest.cpp
@@ -168,7 +168,7 @@
 {
     Okular::Document d(nullptr);
     SearchFinishedReceiver receiver;
-    QSignalSpy spy(&d, SIGNAL(searchFinished(int,Okular::Document::SearchStatus)));
+    QSignalSpy spy(&d, &Okular::Document::searchFinished);
 
     QObject::connect(&d, SIGNAL(searchFinished(int,Okular::Document::SearchStatus)), &receiver, SLOT(searchFinished(int,Okular::Document::SearchStatus)));
     
@@ -243,14 +243,14 @@
     //the Unicode case-folding rules http://www.unicode.org/Public/6.2.0/ucd/CaseFolding.txt).
 
     QVector<QString> text;
-    text << QString::fromUtf8("İ");
+    text << QStringLiteral("İ");
 
     QVector<Okular::NormalizedRect> rect;
     rect << Okular::NormalizedRect(1, 2, 3, 4);
 
     CREATE_PAGE;
 
-    Okular::RegularAreaRect* result = tp->findText(0, QString::fromUtf8("İ"), Okular::FromTop, Qt::CaseInsensitive, nullptr);
+    Okular::RegularAreaRect* result = tp->findText(0, QStringLiteral("İ"), Okular::FromTop, Qt::CaseInsensitive, nullptr);
     QVERIFY(result);
     delete result;
 
diff --git a/autotests/visibilitytest.cpp b/autotests/visibilitytest.cpp
--- a/autotests/visibilitytest.cpp
+++ b/autotests/visibilitytest.cpp
@@ -122,7 +122,7 @@
     verifyTargetStates( false );
 
     // Save the changed states
-    QTemporaryFile saveFile( QString( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
+    QTemporaryFile saveFile( QStringLiteral( "%1/okrXXXXXX.pdf" ).arg( QDir::tempPath() ) );
     QVERIFY( saveFile.open() );
     saveFile.close();
 
diff --git a/core/document.cpp b/core/document.cpp
--- a/core/document.cpp
+++ b/core/document.cpp
@@ -1113,7 +1113,7 @@
 
 void DocumentPrivate::recalculateForms()
 {
-    const QVariant fco = m_parent->metaData(QLatin1String("FormCalculateOrder"));
+    const QVariant fco = m_parent->metaData(QStringLiteral("FormCalculateOrder"));
     const QVector<int> formCalculateOrder = fco.value<QVector<int>>();
     foreach(int formId, formCalculateOrder) {
         for ( uint pageIdx = 0; pageIdx  < m_parent->pages(); pageIdx++ )
@@ -1196,7 +1196,7 @@
     //  -> do this if there are not-yet-migrated annots or forms in docdata/
     if ( m_docdataMigrationNeeded )
     {
-        QDomElement pageList = doc.createElement( "pageList" );
+        QDomElement pageList = doc.createElement( QStringLiteral("pageList") );
         root.appendChild( pageList );
         // OriginalAnnotationPageItems and OriginalFormFieldPageItems tell to
         // store the same unmodified annotation list and form contents that we
@@ -2281,7 +2281,7 @@
     static QVector<KPluginMetaData> result;
     if (result.isEmpty())
     {
-        result = KPluginLoader::findPlugins( QLatin1String ( "okular/generators" ) );
+        result = KPluginLoader::findPlugins( QStringLiteral ( "okular/generators" ) );
     }
     return result;
 }
@@ -2365,7 +2365,7 @@
     if (url.scheme() == QLatin1String("fd"))
     {
         bool ok;
-        fd = url.path().mid(1).toInt(&ok);
+        fd = url.path().midRef(1).toInt(&ok);
         if (!ok)
         {
             return OpenError;
@@ -4230,7 +4230,7 @@
                 const QUrl url = browse->url();
 
                 // fix for #100366, documents with relative links that are the form of http:foo.pdf
-                if ((url.scheme() == "http") && url.host().isEmpty() && url.fileName().endsWith("pdf"))
+                if ((url.scheme() == QLatin1String("http")) && url.host().isEmpty() && url.fileName().endsWith(QLatin1String("pdf")))
                 {
                     d->openRelativeFile(url.fileName());
                     break;
diff --git a/core/documentcommands.cpp b/core/documentcommands.cpp
--- a/core/documentcommands.cpp
+++ b/core/documentcommands.cpp
@@ -156,8 +156,8 @@
 ModifyAnnotationPropertiesCommand::ModifyAnnotationPropertiesCommand( DocumentPrivate* docPriv,
                                                                       Annotation* annotation,
                                                                       int pageNumber,
-                                                                      QDomNode oldProperties,
-                                                                      QDomNode newProperties )
+                                                                      const QDomNode &oldProperties,
+                                                                      const QDomNode &newProperties )
  : m_docPriv( docPriv ),
    m_annotation( annotation ),
    m_pageNumber( pageNumber ),
diff --git a/core/documentcommands_p.h b/core/documentcommands_p.h
--- a/core/documentcommands_p.h
+++ b/core/documentcommands_p.h
@@ -76,8 +76,8 @@
     public:
         ModifyAnnotationPropertiesCommand( Okular::DocumentPrivate* docPriv,  Okular::Annotation*  annotation,
                                                                   int pageNumber,
-                                                                  QDomNode oldProperties,
-                                                                  QDomNode newProperties );
+                                                                  const QDomNode &oldProperties,
+                                                                  const QDomNode &newProperties );
 
         void undo() override;
         void redo() override;
diff --git a/core/fileprinter.cpp b/core/fileprinter.cpp
--- a/core/fileprinter.cpp
+++ b/core/fileprinter.cpp
@@ -31,15 +31,15 @@
 
 using namespace Okular;
 
-int FilePrinter::printFile( QPrinter &printer, const QString file,
+int FilePrinter::printFile(QPrinter &printer, const QString file,
                             QPrinter::Orientation documentOrientation, FileDeletePolicy fileDeletePolicy,
                             PageSelectPolicy pageSelectPolicy, const QString &pageRange )
 {
     return printFile( printer, file, documentOrientation, fileDeletePolicy,
                       pageSelectPolicy, pageRange, ScaleMode::FitToPrintArea );
 }
 
-int FilePrinter::printFile( QPrinter &printer, const QString file,
+int FilePrinter::printFile(QPrinter &printer, const QString file,
                             QPrinter::Orientation documentOrientation,
                             FileDeletePolicy fileDeletePolicy, PageSelectPolicy pageSelectPolicy,
                             const QString &pageRange, ScaleMode scaleMode )
@@ -49,7 +49,7 @@
                             documentOrientation, scaleMode );
 }
 
-int FilePrinter::doPrintFiles( QPrinter &printer, QStringList fileList, FileDeletePolicy fileDeletePolicy,
+int FilePrinter::doPrintFiles(QPrinter &printer, const QStringList fileList, FileDeletePolicy fileDeletePolicy,
                                PageSelectPolicy pageSelectPolicy, const QString &pageRange,
                                QPrinter::Orientation documentOrientation )
 {
@@ -113,8 +113,8 @@
             argList << fileList[0] << printer.outputFileName();
             qCDebug(OkularCoreDebug) << "Executing" << exe << "with arguments" << argList;
             ret = KProcess::execute( exe, argList );
-        } else if ( inputFileInfo.suffix() == "pdf" && printer.outputFormat() == QPrinter::NativeFormat && pdf2psAvailable() ) {
-            exe = "pdf2ps";
+        } else if ( inputFileInfo.suffix() == QLatin1String("pdf") && printer.outputFormat() == QPrinter::NativeFormat && pdf2psAvailable() ) {
+            exe = QStringLiteral("pdf2ps");
             argList << fileList[0] << printer.outputFileName();
             qCDebug(OkularCoreDebug) << "Executing" << exe << "with arguments" << argList;
             ret = KProcess::execute( exe, argList );
diff --git a/core/script/kjs_app.cpp b/core/script/kjs_app.cpp
--- a/core/script/kjs_app.cpp
+++ b/core/script/kjs_app.cpp
@@ -101,7 +101,7 @@
 #elif defined(Q_OS_MAC)
     return KJSString( QString::fromLatin1( "MAC" ) );
 #else
-    return KJSString( QLatin1String( "UNIX" ) );
+    return KJSString( QStringLiteral( "UNIX" ) );
 #endif
 }
 
@@ -135,13 +135,13 @@
 static KJSObject appGetViewerType( KJSContext *, void * )
 {
     // faking a bit...
-    return KJSString( QLatin1String( "Reader" ) );
+    return KJSString( QStringLiteral( "Reader" ) );
 }
 
 static KJSObject appGetViewerVariation( KJSContext *, void * )
 {
     // faking a bit...
-    return KJSString( QLatin1String( "Reader" ) );
+    return KJSString( QStringLiteral( "Reader" ) );
 }
 
 static KJSObject appGetViewerVersion( KJSContext *, void * )
diff --git a/core/scripter.cpp b/core/scripter.cpp
--- a/core/scripter.cpp
+++ b/core/scripter.cpp
@@ -59,7 +59,7 @@
     static QString builtInScript;
     if ( builtInScript.isNull() )
     {
-        QFile builtInResource ( ":/script/builtin.js" );
+        QFile builtInResource ( QStringLiteral(":/script/builtin.js") );
         if (!builtInResource.open( QIODevice::ReadOnly ))
         {
             qCDebug(OkularCoreDebug) << "failed to load builtin script";
diff --git a/generators/epub/converter.cpp b/generators/epub/converter.cpp
--- a/generators/epub/converter.cpp
+++ b/generators/epub/converter.cpp
@@ -381,7 +381,7 @@
         } else { // load missing resource
           char *data = 0;
           //epub_get_data can't handle whitespace url encodings
-          QByteArray ba = link.replace("%20", " ").toLatin1();
+          QByteArray ba = link.replace(QLatin1String("%20"), QLatin1String(" ")).toLatin1();
           const char *clinkClean = ba.data(); 
           int size = epub_get_data(mTextDocument->getEpub(), clinkClean, &data);
 
diff --git a/generators/markdown/generator_md.cpp b/generators/markdown/generator_md.cpp
--- a/generators/markdown/generator_md.cpp
+++ b/generators/markdown/generator_md.cpp
@@ -28,7 +28,7 @@
 {
     Okular::TextDocumentSettings *mdSettings = generalSettings();
 
-    mdSettings->addItemBool( "SmartyPants", s_isFancyPantsEnabled, true );
+    mdSettings->addItemBool( QStringLiteral("SmartyPants"), s_isFancyPantsEnabled, true );
     mdSettings->load();
     s_wasFancyPantsEnabled = s_isFancyPantsEnabled;
 }
@@ -55,7 +55,7 @@
     Okular::TextDocumentSettingsWidget *widget = new Okular::TextDocumentSettingsWidget();
 
     QCheckBox *enableSmartyPants = new QCheckBox( dlg );
-    enableSmartyPants->setObjectName( QString::fromUtf8( "kcfg_SmartyPants" ) );
+    enableSmartyPants->setObjectName( QStringLiteral( "kcfg_SmartyPants" ) );
     widget->addRow( i18n("Enable SmartyPants formatting"), enableSmartyPants );
 
     dlg->addPage( widget, generalSettings(), i18n("Markdown"), QStringLiteral("text-markdown"), i18n("Markdown Backend Configuration") );
diff --git a/generators/mobipocket/mobidocument.cpp b/generators/mobipocket/mobidocument.cpp
--- a/generators/mobipocket/mobidocument.cpp
+++ b/generators/mobipocket/mobidocument.cpp
@@ -55,7 +55,7 @@
 {
   if (type!=QTextDocument::ImageResource || name.scheme()!=QString(QStringLiteral("pdbrec"))) return QVariant();
   bool ok;
-  quint16 recnum=name.path().mid(1).toUShort(&ok);
+  quint16 recnum=name.path().midRef(1).toUShort(&ok);
   if (!ok || recnum>=doc->imageCount()) return QVariant();
    
   QVariant resource;
diff --git a/mobile/app/main.cpp b/mobile/app/main.cpp
--- a/mobile/app/main.cpp
+++ b/mobile/app/main.cpp
@@ -69,7 +69,7 @@
     paths[QStringLiteral("home")] = QStandardPaths::writableLocation(QStandardPaths::HomeLocation);
     engine.rootContext()->setContextProperty(QStringLiteral("userPaths"), paths);
 
-    engine.setBaseUrl(QUrl("qrc:/package/contents/ui/"));
-    engine.load(QUrl("qrc:/package/contents/ui/main.qml"));
+    engine.setBaseUrl(QUrl(QStringLiteral("qrc:/package/contents/ui/")));
+    engine.load(QUrl(QStringLiteral("qrc:/package/contents/ui/main.qml")));
     return app.exec();
 }
diff --git a/mobile/components/documentitem.cpp b/mobile/components/documentitem.cpp
--- a/mobile/components/documentitem.cpp
+++ b/mobile/components/documentitem.cpp
@@ -59,7 +59,7 @@
     //TODO: password
     QMimeDatabase db;
 
-    const QString path = url.isLocalFile() ? url.toLocalFile() : QLatin1String("-");
+    const QString path = url.isLocalFile() ? url.toLocalFile() : QStringLiteral("-");
 
     m_document->openDocument(path, url, db.mimeTypeForUrl(url));
 
diff --git a/mobile/components/pageitem.cpp b/mobile/components/pageitem.cpp
--- a/mobile/components/pageitem.cpp
+++ b/mobile/components/pageitem.cpp
@@ -39,7 +39,7 @@
 
 PageItem::PageItem(QQuickItem *parent)
     : QQuickItem(parent),
-      Okular::View( QLatin1String( "PageView" ) ),
+      Okular::View( QStringLiteral( "PageView" ) ),
       m_page(nullptr),
       m_smooth(false),
       m_bookmarked(false),
diff --git a/part.cpp b/part.cpp
--- a/part.cpp
+++ b/part.cpp
@@ -204,16 +204,16 @@
     if ( compressedMimeMap.isEmpty() )
     {
         std::unique_ptr< KFilterBase > f;
-        compressedMimeMap[ QLatin1String( "image/x-gzeps" ) ] = KFilterDev::GZip;
+        compressedMimeMap[ QStringLiteral( "image/x-gzeps" ) ] = KFilterDev::GZip;
         // check we can read bzip2-compressed files
         f.reset( KCompressionDevice::filterForCompressionType( KCompressionDevice::BZip2 ) );
         if ( f.get() )
         {
             supportBzip = true;
-            compressedMimeMap[ QLatin1String( "application/x-bzpdf" ) ] = KFilterDev::BZip2;
-            compressedMimeMap[ QLatin1String( "application/x-bzpostscript" ) ] = KFilterDev::BZip2;
-            compressedMimeMap[ QLatin1String( "application/x-bzdvi" ) ] = KFilterDev::BZip2;
-            compressedMimeMap[ QLatin1String( "image/x-bzeps" ) ] = KFilterDev::BZip2;
+            compressedMimeMap[ QStringLiteral( "application/x-bzpdf" ) ] = KFilterDev::BZip2;
+            compressedMimeMap[ QStringLiteral( "application/x-bzpostscript" ) ] = KFilterDev::BZip2;
+            compressedMimeMap[ QStringLiteral( "application/x-bzdvi" ) ] = KFilterDev::BZip2;
+            compressedMimeMap[ QStringLiteral( "image/x-bzeps" ) ] = KFilterDev::BZip2;
         }
         // check if we can read XZ-compressed files
         f.reset( KCompressionDevice::filterForCompressionType( KCompressionDevice::Xz ) );
@@ -1566,8 +1566,8 @@
     m_find->setEnabled( ok && canSearch );
     m_findNext->setEnabled( ok && canSearch );
     m_findPrev->setEnabled( ok && canSearch );
-    if( m_save ) m_save->setEnabled( ok && !( isstdin || mime.inherits( "inode/directory" ) ) );
-    if( m_saveAs ) m_saveAs->setEnabled( ok && !( isstdin || mime.inherits( "inode/directory" ) ) );
+    if( m_save ) m_save->setEnabled( ok && !( isstdin || mime.inherits( QStringLiteral("inode/directory") ) ) );
+    if( m_saveAs ) m_saveAs->setEnabled( ok && !( isstdin || mime.inherits( QStringLiteral("inode/directory") ) ) );
     emit enablePrintAction( ok && m_document->printingSupport() != Okular::Document::NoPrinting );
     m_printPreview->setEnabled( ok && m_document->printingSupport() != Okular::Document::NoPrinting );
     m_showProperties->setEnabled( ok );
@@ -2439,10 +2439,10 @@
     {
         QAction *separatorAction = contextMenu->addSeparator();
         separatorAction->setObjectName(QStringLiteral("OkularPrivateRenameBookmarkActions"));
-        QAction *renameAction = contextMenu->addAction( QIcon::fromTheme( QStringLiteral("edit-rename") ), i18n( "Rename this Bookmark" ), this, SLOT(slotRenameBookmarkFromMenu()) );
+        QAction *renameAction = contextMenu->addAction( QIcon::fromTheme( QStringLiteral("edit-rename") ), i18n( "Rename this Bookmark" ), this, &Part::slotRenameBookmarkFromMenu );
         renameAction->setData(ba->property("htmlRef").toString());
         renameAction->setObjectName(QStringLiteral("OkularPrivateRenameBookmarkActions"));
-        QAction *deleteAction = contextMenu->addAction( QIcon::fromTheme( QStringLiteral("list-remove") ), i18n("Remove this Bookmark"), this, SLOT(slotRemoveBookmarkFromMenu()));
+        QAction *deleteAction = contextMenu->addAction( QIcon::fromTheme( QStringLiteral("list-remove") ), i18n("Remove this Bookmark"), this, &Part::slotRemoveBookmarkFromMenu);
         deleteAction->setData(ba->property("htmlRef").toString());
         deleteAction->setObjectName(QStringLiteral("OkularPrivateRenameBookmarkActions"));
     }
@@ -2667,7 +2667,7 @@
                 const int result = KMessageBox::warningYesNoList( widget(),
                     warningMessage,
                     listOfwontSaves, i18n( "Warning" ),
-                    KGuiItem( i18n( "Save as Okular document archive..." ), "document-save-as" ), // <- KMessageBox::Yes
+                    KGuiItem( i18n( "Save as Okular document archive..." ), QStringLiteral("document-save-as") ), // <- KMessageBox::Yes
                     KStandardGuiItem::cancel() );
 
                 switch (result)
@@ -2690,8 +2690,8 @@
                 const int result = KMessageBox::warningYesNoCancelList( widget(),
                     warningMessage,
                     listOfwontSaves, i18n( "Warning" ),
-                    KGuiItem( i18n( "Save as Okular document archive..." ), "document-save-as" ), // <- KMessageBox::Yes
-                    KGuiItem( continueMessage, "arrow-right" ) ); // <- KMessageBox::NO
+                    KGuiItem( i18n( "Save as Okular document archive..." ), QStringLiteral("document-save-as") ), // <- KMessageBox::Yes
+                    KGuiItem( continueMessage, QStringLiteral("arrow-right") ) ); // <- KMessageBox::NO
 
                 switch (result)
                 {
@@ -3675,7 +3675,7 @@
         KMessageBox::error(widget(), i18n("There was a problem sharing the document: %1", message),
                            i18n("Share"));
     } else {
-        const QString url = output["url"].toString();
+        const QString url = output[QStringLiteral("url")].toString();
         if (url.isEmpty()) {
             m_pageView->displayMessage(i18n("Document shared successfully"));
         } else {
diff --git a/shell/shell.cpp b/shell/shell.cpp
--- a/shell/shell.cpp
+++ b/shell/shell.cpp
@@ -572,16 +572,16 @@
 {
     if (m_tabs.count() > 1)
     {
-        const QString dontAskAgainName = "ShowTabWarning";
+        const QString dontAskAgainName = QStringLiteral("ShowTabWarning");
         KMessageBox::ButtonCode dummy;
         if (shouldBeShownYesNo(dontAskAgainName, dummy))
         {
             QDialog *dialog = new QDialog(this);
             dialog->setWindowTitle(i18n("Confirm Close"));
 
             QDialogButtonBox *buttonBox = new QDialogButtonBox(dialog);
             buttonBox->setStandardButtons(QDialogButtonBox::Yes | QDialogButtonBox::No);
-            KGuiItem::assign(buttonBox->button(QDialogButtonBox::Yes), KGuiItem(i18n("Close Tabs"), "tab-close"));
+            KGuiItem::assign(buttonBox->button(QDialogButtonBox::Yes), KGuiItem(i18n("Close Tabs"), QStringLiteral("tab-close")));
             KGuiItem::assign(buttonBox->button(QDialogButtonBox::No), KStandardGuiItem::cancel());
 
 
diff --git a/ui/annotwindow.h b/ui/annotwindow.h
--- a/ui/annotwindow.h
+++ b/ui/annotwindow.h
@@ -64,7 +64,7 @@
         void slotOptionBtn();
         void slotsaveWindowText();
         void renderLatex( bool render );
-        void slotHandleContentsChangedByUndoRedo( Okular::Annotation* annot, QString contents, int cursorPos, int anchorPos);
+        void slotHandleContentsChangedByUndoRedo( Okular::Annotation* annot, const QString &contents, int cursorPos, int anchorPos);
 
     Q_SIGNALS:
         void containsLatex( bool );
diff --git a/ui/annotwindow.cpp b/ui/annotwindow.cpp
--- a/ui/annotwindow.cpp
+++ b/ui/annotwindow.cpp
@@ -198,7 +198,7 @@
     setAutoFillBackground( true );
     setFrameStyle( Panel | Raised );
     setAttribute( Qt::WA_DeleteOnClose );
-    setObjectName("AnnotWindow");
+    setObjectName(QStringLiteral("AnnotWindow"));
 
     const bool canEditAnnotation = m_document->canModifyPageAnnotation( annot );
 
@@ -421,7 +421,7 @@
     }
 }
 
-void AnnotWindow::slotHandleContentsChangedByUndoRedo(Okular::Annotation* annot, QString contents, int cursorPos, int anchorPos)
+void AnnotWindow::slotHandleContentsChangedByUndoRedo(Okular::Annotation* annot, const QString &contents, int cursorPos, int anchorPos)
 {
     if ( annot != m_annot )
     {
diff --git a/ui/certificateviewer.cpp b/ui/certificateviewer.cpp
--- a/ui/certificateviewer.cpp
+++ b/ui/certificateviewer.cpp
@@ -63,7 +63,7 @@
     {
         for ( const QString &attribute : attributes )
         {
-            const QRegularExpression re( QString( "(.*),\\s*(%1=.*)" ).arg( attribute ), QRegularExpression::DotMatchesEverythingOption );
+            const QRegularExpression re( QStringLiteral( "(.*),\\s*(%1=.*)" ).arg( attribute ), QRegularExpression::DotMatchesEverythingOption );
             const QRegularExpressionMatch match = re.match( t );
             if ( match.hasMatch() )
             {
@@ -81,15 +81,15 @@
     QStringList result = text;
     for ( QString &t : result )
     {
-        t.replace( "\\,", "," );
+        t.replace( QLatin1String("\\,"), QLatin1String(",") );
     }
 
     // Clean up quoted attributes
     for ( QString &t : result )
     {
         for ( const QString &attribute : attributes )
         {
-            const QRegularExpression re( QString( "%1=\"(.*)\"" ).arg( attribute ) );
+            const QRegularExpression re( QStringLiteral( "%1=\"(.*)\"" ).arg( attribute ) );
             const QRegularExpressionMatch match = re.match( t );
             if ( match.hasMatch() )
             {
diff --git a/ui/embeddedfilesdialog.cpp b/ui/embeddedfilesdialog.cpp
--- a/ui/embeddedfilesdialog.cpp
+++ b/ui/embeddedfilesdialog.cpp
@@ -60,7 +60,7 @@
 
 	mUser2Button = new QPushButton;
 	buttonBox->addButton(mUser2Button, QDialogButtonBox::ActionRole);
-	KGuiItem::assign(mUser2Button, KGuiItem(i18nc("@action:button", "View"), "document-open"));
+	KGuiItem::assign(mUser2Button, KGuiItem(i18nc("@action:button", "View"), QStringLiteral("document-open")));
 	mUser2Button->setEnabled(false);
 
 	m_tw = new QTreeWidget(this);
@@ -183,7 +183,7 @@
 		+ QDir::separator()
 		+ fileInfo.baseName()
 		+ ".XXXXXX"
-		+ (fileInfo.completeSuffix().isEmpty() ? QString("") : "." + fileInfo.completeSuffix()) // krazy:exclude=doublequote_chars
+		+ (fileInfo.completeSuffix().isEmpty() ? QStringLiteral("") : "." + fileInfo.completeSuffix()) // krazy:exclude=doublequote_chars
 	);
 	GuiUtils::writeEmbeddedFile( ef, this, *tmpFile );
 
diff --git a/ui/fileprinterpreview.cpp b/ui/fileprinterpreview.cpp
--- a/ui/fileprinterpreview.cpp
+++ b/ui/fileprinterpreview.cpp
@@ -91,7 +91,7 @@
                                            QStringLiteral("KParts/ReadOnlyPart"),
                                            QStringLiteral("[DesktopEntryName] == 'okularghostview'"));
     } else {
-        offers = KMimeTypeTrader::self()->query("application/pdf", "KParts/ReadOnlyPart");
+        offers = KMimeTypeTrader::self()->query(QStringLiteral("application/pdf"), QStringLiteral("KParts/ReadOnlyPart"));
     }
 
     KService::List::ConstIterator it = offers.constBegin();
diff --git a/ui/pageview.cpp b/ui/pageview.cpp
--- a/ui/pageview.cpp
+++ b/ui/pageview.cpp
@@ -299,7 +299,7 @@
  */
 PageView::PageView( QWidget *parent, Okular::Document *document )
     : QAbstractScrollArea( parent )
-    , Okular::View( QLatin1String( "PageView" ) )
+    , Okular::View( QStringLiteral( "PageView" ) )
 {
     // create and initialize private storage structure
     d = new PageViewPrivate( this );
@@ -2776,7 +2776,7 @@
 
             // popup that ask to copy:text and copy/save:image
             QMenu menu( this );
-            menu.setObjectName("PopupMenu");
+            menu.setObjectName(QStringLiteral("PopupMenu"));
             QAction *textToClipboard = nullptr;
 #ifdef HAVE_SPEECH
             QAction *speakText = nullptr;
@@ -2787,7 +2787,7 @@
             {
                 menu.addAction( new OKMenuTitle( &menu, i18np( "Text (1 character)", "Text (%1 characters)", selectedText.length() ) ) );
                 textToClipboard = menu.addAction( QIcon::fromTheme(QStringLiteral("edit-copy")), i18n( "Copy to Clipboard" ) );
-                textToClipboard->setObjectName("CopyTextToClipboard");
+                textToClipboard->setObjectName(QStringLiteral("CopyTextToClipboard"));
                 bool copyAllowed = d->document->isAllowed( Okular::AllowCopy );
                 if ( !copyAllowed )
                 {
@@ -3094,13 +3094,13 @@
                                 {
                                     const QString squeezedText = KStringHandler::rsqueeze( url, 30 );
                                     httpLink = menu->addAction( i18n( "Go to '%1'", squeezedText ) );
-                                    httpLink->setObjectName("GoToAction");
+                                    httpLink->setObjectName(QStringLiteral("GoToAction"));
                                 }
                             }
                         }
 
                         if ( menu ) {
-                            menu->setObjectName("PopupMenu");
+                            menu->setObjectName(QStringLiteral("PopupMenu"));
 
                             QAction *choice = menu->exec( e->globalPos() );
                             // check if the user really selected an action
@@ -4411,7 +4411,7 @@
         const Okular::Action * link = static_cast< const Okular::Action * >( rect->object() );
         // creating the menu and its actions
         QAction * processLink = menu->addAction( i18n( "Follow This Link" ) );
-        processLink->setObjectName("ProcessLinkAction");
+        processLink->setObjectName(QStringLiteral("ProcessLinkAction"));
         if ( link->actionType() == Okular::Action::Sound ) {
             processLink->setText( i18n( "Play this Sound" ) );
             if ( Okular::AudioPlayer::instance()->state() == Okular::AudioPlayer::PlayingState ) {
@@ -4426,7 +4426,7 @@
         if ( dynamic_cast< const Okular::BrowseAction * >( link ) )
         {
             QAction * actCopyLinkLocation = menu->addAction( QIcon::fromTheme( QStringLiteral("edit-copy") ), i18n( "Copy Link Address" ) );
-            actCopyLinkLocation->setObjectName("CopyLinkLocationAction");
+            actCopyLinkLocation->setObjectName(QStringLiteral("CopyLinkLocationAction"));
             connect( actCopyLinkLocation, &QAction::triggered, [ link ]() {
                 const Okular::BrowseAction * browseLink = static_cast< const Okular::BrowseAction * >( link );
                 QClipboard *cb = QApplication::clipboard();
diff --git a/ui/pageviewannotator.cpp b/ui/pageviewannotator.cpp
--- a/ui/pageviewannotator.cpp
+++ b/ui/pageviewannotator.cpp
@@ -141,7 +141,7 @@
             }
         }
 
-        void addInPlaceTextAnnotation( Okular::Annotation * &ann, const QString summary, const QString content, Okular::TextAnnotation::InplaceIntent inplaceIntent )
+        void addInPlaceTextAnnotation( Okular::Annotation * &ann, const QString &summary, const QString &content, Okular::TextAnnotation::InplaceIntent inplaceIntent )
         {
             Okular::TextAnnotation * ta = new Okular::TextAnnotation();
             ann = ta;
@@ -1126,7 +1126,7 @@
     // Load HiDPI variant on HiDPI screen
     QString imageVariant;
     if ( qApp->devicePixelRatio() > 1.05 ) {
-        imageVariant = "@2x";
+        imageVariant = QStringLiteral("@2x");
     }
 
     // Load base pixmap. We'll draw on top of it
diff --git a/ui/presentationwidget.cpp b/ui/presentationwidget.cpp
--- a/ui/presentationwidget.cpp
+++ b/ui/presentationwidget.cpp
@@ -1754,8 +1754,8 @@
     QString reason = i18nc( "Reason for inhibiting the screensaver activation, when the presentation mode is active", "Giving a presentation" );
 
     if (!m_screenInhibitCookie) {
-        QDBusMessage message = QDBusMessage::createMethodCall("org.freedesktop.ScreenSaver", "/ScreenSaver",
-                                                              "org.freedesktop.ScreenSaver", "Inhibit");
+        QDBusMessage message = QDBusMessage::createMethodCall(QStringLiteral("org.freedesktop.ScreenSaver"), QStringLiteral("/ScreenSaver"),
+                                                              QStringLiteral("org.freedesktop.ScreenSaver"), QStringLiteral("Inhibit"));
         message << QCoreApplication::applicationName();
         message << reason;
 
@@ -1800,8 +1800,8 @@
     }
 
     if (m_screenInhibitCookie) {
-        QDBusMessage message = QDBusMessage::createMethodCall("org.freedesktop.ScreenSaver", "/ScreenSaver",
-                                                              "org.freedesktop.ScreenSaver", "UnInhibit");
+        QDBusMessage message = QDBusMessage::createMethodCall(QStringLiteral("org.freedesktop.ScreenSaver"), QStringLiteral("/ScreenSaver"),
+                                                              QStringLiteral("org.freedesktop.ScreenSaver"), QStringLiteral("UnInhibit"));
         message << m_screenInhibitCookie;
 
         QDBusPendingReply<uint> reply = QDBusConnection::sessionBus().asyncCall(message);