diff --git a/src/canvas.cpp b/src/canvas.cpp
--- a/src/canvas.cpp
+++ b/src/canvas.cpp
@@ -124,7 +124,7 @@
 void Canvas::drawLine(double x1, double y1, double x2, double y2)
 {
 	if (penWidthIsZero) return;
-	QGraphicsLineItem* line = new QGraphicsLineItem(QLineF(x1, y1, x2, y2), 0);
+	QGraphicsLineItem* line = new QGraphicsLineItem(QLineF(x1, y1, x2, y2), nullptr);
 	_scene->addItem(line);
 	line->setPen(*pen);
 	lines.append(line);
diff --git a/src/editor.cpp b/src/editor.cpp
--- a/src/editor.cpp
+++ b/src/editor.cpp
@@ -243,7 +243,7 @@
 		delete savefile;
         if (!url.isLocalFile())
            {
-            KIO::StoredTransferJob *job = KIO::storedPut(savefile, url, -1, 0);
+            KIO::StoredTransferJob *job = KIO::storedPut(savefile, url, -1, nullptr);
                  if(job->exec()){
                     setCurrentUrl(url);
                     editor->document()->setModified(false);
@@ -300,7 +300,7 @@
 	}
 	if (fdialog->exec() == QDialog::Accepted && !fdialog->pattern().isEmpty()) {
 		long kOpts = fdialog->options();
-		QTextDocument::FindFlags qOpts = 0;
+		QTextDocument::FindFlags qOpts = nullptr;
 		if (kOpts & KFind::CaseSensitive)  { qOpts |= QTextDocument::FindCaseSensitively; }
 		if (kOpts & KFind::FindBackwards)  { qOpts |= QTextDocument::FindBackward; }
 		if (kOpts & KFind::WholeWordsOnly) { qOpts |= QTextDocument::FindWholeWords; }
@@ -312,7 +312,7 @@
 {
 	if (!fdialog->pattern().isEmpty()) {
 		long kOpts = fdialog->options();
-		QTextDocument::FindFlags qOpts = 0;
+		QTextDocument::FindFlags qOpts = nullptr;
 		if (kOpts & KFind::CaseSensitive)  { qOpts |= QTextDocument::FindCaseSensitively; }
 		if (kOpts & KFind::FindBackwards)  { qOpts |= QTextDocument::FindBackward; }
 		if (kOpts & KFind::WholeWordsOnly) { qOpts |= QTextDocument::FindWholeWords; }
@@ -324,7 +324,7 @@
 {
 	if(!fdialog->pattern().isEmpty()) {
 		long kOpts = fdialog->options();
-		QTextDocument::FindFlags qOpts = 0;
+		QTextDocument::FindFlags qOpts = nullptr;
 		if (kOpts & KFind::CaseSensitive)    { qOpts |= QTextDocument::FindCaseSensitively; }
 		// search in the opposite direction as findNext()
 		if (!(kOpts & KFind::FindBackwards)) { qOpts |= QTextDocument::FindBackward; }
@@ -386,7 +386,7 @@
 		token = tokenizer->getToken();
 	}
 	delete token;
-	return 0;
+	return nullptr;
 }
 
 
@@ -424,7 +424,7 @@
 			default:                escaped = token->look().toHtmlEscaped(); break;
 		}
 		format = highlighter->tokenToFormat(token);
-		if (format != 0) {
+		if (format) {
 			bool bold = format->fontWeight() > 50;
 			html += QString("<span style=\"color: %1;%2\">%3</span>")
 				.arg(format->foreground().color().name())
diff --git a/src/errordialog.cpp b/src/errordialog.cpp
--- a/src/errordialog.cpp
+++ b/src/errordialog.cpp
@@ -35,7 +35,7 @@
 ErrorDialog::ErrorDialog(QWidget* parent)
 	: QDialog(parent)
 {
-	errorList = 0;
+	errorList = nullptr;
 
 	setWindowTitle(i18n("Errors"));
 	setModal(false);
@@ -94,7 +94,7 @@
 void ErrorDialog::clear()
 {
 	disable();
-	errorList = 0;
+	errorList = nullptr;
 	errorTable->clearContents();
 
 	// put a friendly 'nothing to see here' notice in the empty table
@@ -113,7 +113,7 @@
 
 void ErrorDialog::enable()
 {
-	Q_ASSERT (errorList != 0);
+	Q_ASSERT (errorList);
 	errorTable->setEnabled(true);
 	m_buttonBox->button(QDialogButtonBox::Help)->setEnabled(true);
 	connect(errorTable, &QTableWidget::itemSelectionChanged, this, &ErrorDialog::selectedErrorChangedProxy);
@@ -151,7 +151,7 @@
 
 void ErrorDialog::selectedErrorChangedProxy()
 {
-	Q_ASSERT (errorList != 0);
+	Q_ASSERT (errorList);
 	const Token* t = &errorList->at(errorTable->selectedItems().first()->row()).token();
 	emit currentlySelectedError(t->startRow(), t->startCol(), t->endRow(), t->endCol());
 	// //qDebug() << "EMITTED: " << t->startRow() << ", " << t->startCol() << ", " << t->endRow() << ", " << t->endCol();
diff --git a/src/highlighter.cpp b/src/highlighter.cpp
--- a/src/highlighter.cpp
+++ b/src/highlighter.cpp
@@ -82,7 +82,7 @@
 	QTextCharFormat* format;
 	while (token->type() != Token::EndOfInput) {
 		format = tokenToFormat(token);
-		if (format != 0) {
+		if (format) {
 			if (cursorIndex == -1)  // does not return, but keeps running
 				setFormat(token->startCol() - 1, token->endCol() - token->startCol(), *format);
 			else if (cursorIndex >= token->startCol() && cursorIndex <= token->endCol())
@@ -92,7 +92,7 @@
 		token = tokenizer->getToken();
 	}
 	delete token;
-	return 0;
+	return nullptr;
 }
 
 QTextCharFormat* Highlighter::tokenToFormat(Token* token)
@@ -113,9 +113,9 @@
 		case Token::AssignmentCategory:        return &assignmentFormat;
 
 		// do nothing with these...
-		case Token::ParenthesisCategory:       return 0;
-		case Token::FunctionCallCategory:      return 0;
-		case Token::ArgumentSeparatorCategory: return 0;
+		case Token::ParenthesisCategory:       return nullptr;
+		case Token::FunctionCallCategory:      return nullptr;
+		case Token::ArgumentSeparatorCategory: return nullptr;
 	}
-	return 0;
+	return nullptr;
 }
diff --git a/src/inspector.cpp b/src/inspector.cpp
--- a/src/inspector.cpp
+++ b/src/inspector.cpp
@@ -71,7 +71,7 @@
 // 	functionMap = new QHash<QString, QTableWidgetItem*>();
 // 	treeMap = new QHash<TreeNode*, QTableWidgetItem*>();
 
-	currentlyMarkedTreeItem = 0;
+	currentlyMarkedTreeItem = nullptr;
 
 	disable();
 
@@ -252,7 +252,7 @@
 	QTreeWidgetItem* result = new QTreeWidgetItem();
 	result->setText(0, node->token()->look());
 	QTextCharFormat* format = highlighter->tokenToFormat(node->token());
-	if (format != 0) {
+	if (format) {
 		result->setForeground(0, format->foreground());
 		QFont font(QFontDatabase::systemFont(QFontDatabase::FixedFont));
 		font.setBold(format->font().bold());
@@ -270,7 +270,7 @@
 int Inspector::findVariable(const QString& name)
 {
 	QTableWidgetItem* item = variableMap[name];
-	if (item == 0) return -1;
+	if (!item) return -1;
 	return item->row();
 
 // old implementation before we had a variableMap
@@ -308,9 +308,9 @@
 
 void Inspector::clearTreeMark()
 {
-	if (currentlyMarkedTreeItem == 0) return;
+	if (!currentlyMarkedTreeItem) return;
 	currentlyMarkedTreeItem->setBackground(0, previousTreeBackground);
-	currentlyMarkedTreeItem = 0;
+	currentlyMarkedTreeItem = nullptr;
 }
 
 void Inspector::clearAllMarks()
diff --git a/src/main.cpp b/src/main.cpp
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -106,7 +106,7 @@
 
 		///////////////// run in DBUS mode /////////////////
 		Translator::instance()->setLanguage();
-		new Interpreter(0, true);
+		new Interpreter(nullptr, true);
 		
 		return app.exec();
 
@@ -202,7 +202,7 @@
 		  // free some memory
 
 		// init the interpreter
-		Interpreter* interpreter = new Interpreter(0, true);  // set testing to true
+		Interpreter* interpreter = new Interpreter(nullptr, true);  // set testing to true
 		interpreter->initialize(localizedScript);
 
 		// install the echoer
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -71,7 +71,7 @@
 
 	connect(errorDialog, &ErrorDialog::currentlySelectedError, editor, &Editor::markCurrentError);
 
-	colorPicker = 0;
+	colorPicker = nullptr;
 
 	statusBar()->showMessage(i18nc("@info:status the application is ready for commands", "Ready"));
 	updateContentName();  // also sets the window caption to 'untitled'
@@ -136,7 +136,7 @@
 }
 void MainWindow::showColorPicker()
 {
-	if (colorPicker == 0) {
+	if (!colorPicker) {
 		colorPicker = new ColorPicker(this);
 		connect(colorPicker, &ColorPicker::pasteText, editor, &Editor::insertPlainText);
 	}
@@ -762,11 +762,11 @@
 
 	Token* cursorToken = editor->currentToken();
 	QString desc;
-	if (cursorToken != 0) {
+	if (cursorToken) {
 		QString look = cursorToken->look();
 		int cat = cursorToken->category();
 		delete cursorToken;
-		cursorToken = 0;
+		cursorToken = nullptr;
 		KLocalizedString layout = ki18n("\"%1\" <%2>");
 		switch (cat) {
 			// not showing the look (only the name):