diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 40db4aa6d3..6d25d51908 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -664,7 +664,6 @@ void Buffer::cloneWithChildren(BufferMap & bufmap, CloneList_ptr clones) const
 		buffer_clone->setChild(dit, child_clone);
 	}
 	buffer_clone->d->macro_lock = false;
-	return;
 }
 
 
@@ -4010,10 +4009,7 @@ InsetLabel const * Buffer::insetLabel(docstring const & label,
 
 bool Buffer::activeLabel(docstring const & label) const
 {
-	if (!insetLabel(label, true))
-		return false;
-
-	return true;
+	return insetLabel(label, true) != nullptr;
 }
 
 
diff --git a/src/BufferParams.cpp b/src/BufferParams.cpp
index b5ae2d4cad..58a02c8683 100644
--- a/src/BufferParams.cpp
+++ b/src/BufferParams.cpp
@@ -1373,9 +1373,9 @@ void BufferParams::writeFile(ostream & os, Buffer const * buf) const
 	if (!lineno_opts.empty())
 		os << "\\lineno_options " << lineno_opts << '\n';
 
-	if (isbackgroundcolor == true)
+	if (isbackgroundcolor)
 		os << "\\backgroundcolor " << lyx::X11hexname(backgroundcolor) << '\n';
-	if (isfontcolor == true)
+	if (isfontcolor)
 		os << "\\fontcolor " << lyx::X11hexname(fontcolor) << '\n';
 	if (notefontcolor != lyx::rgbFromHexName("#cccccc"))
 		os << "\\notefontcolor " << lyx::X11hexname(notefontcolor) << '\n';
@@ -1979,7 +1979,7 @@ bool BufferParams::writeLaTeX(otexstream & os, LaTeXFeatures & features,
 	}
 
 	// only output when the background color is not default
-	if (isbackgroundcolor == true) {
+	if (isbackgroundcolor) {
 		// only require color here, the background color will be defined
 		// in LaTeXFeatures.cpp to avoid interferences with the LaTeX
 		// package pdfpages
@@ -1988,7 +1988,7 @@ bool BufferParams::writeLaTeX(otexstream & os, LaTeXFeatures & features,
 	}
 
 	// only output when the font color is not default
-	if (isfontcolor == true) {
+	if (isfontcolor) {
 		// only require color here, the font color will be defined
 		// in LaTeXFeatures.cpp to avoid interferences with the LaTeX
 		// package pdfpages
diff --git a/src/DepTable.cpp b/src/DepTable.cpp
index 47daf39113..853edf22c8 100644
--- a/src/DepTable.cpp
+++ b/src/DepTable.cpp
@@ -228,7 +228,7 @@ bool DepTable::read(FileName const & f)
 
 		deplist[FileName(nome)] = di;
 	}
-	return deplist.size();
+	return !deplist.empty();
 }
 
 
diff --git a/src/ErrorList.cpp b/src/ErrorList.cpp
index 1613ce7e61..7022c7bcf5 100644
--- a/src/ErrorList.cpp
+++ b/src/ErrorList.cpp
@@ -32,7 +32,7 @@ ErrorItem::ErrorItem(docstring const & error_, docstring const & description_,
 
 
 ErrorItem::ErrorItem()
-	: start(TexRow::text_none), end(TexRow::text_none), buffer(0)
+	: start(TexRow::text_none), end(TexRow::text_none), buffer(nullptr)
 {}
 
 
diff --git a/src/Font.cpp b/src/Font.cpp
index 327bc1821b..fda0854fe1 100644
--- a/src/Font.cpp
+++ b/src/Font.cpp
@@ -864,7 +864,7 @@ ostream & operator<<(ostream & os, FontInfo const & f)
 ostream & operator<<(ostream & os, Font const & font)
 {
 	return os << font.bits_
-		<< " lang: " << (font.lang_ ? font.lang_->lang() : nullptr);
+		<< " lang: " << (font.lang_ ? font.lang_->lang() : "");
 }
 
 
diff --git a/src/HunspellChecker.cpp b/src/HunspellChecker.cpp
index dcdc1bbbd7..015973e1f4 100644
--- a/src/HunspellChecker.cpp
+++ b/src/HunspellChecker.cpp
@@ -234,11 +234,11 @@ Hunspell * HunspellChecker::Private::lookup(Language const * lang)
 }
 
 
-Hunspell * HunspellChecker::Private::addSpeller(Language const * lang,string & path)
+Hunspell * HunspellChecker::Private::addSpeller(Language const * lang, string & path)
 {
 	if (!haveDictionary(lang, path)) {
-		spellers_[lang->lang()] = 0;
-		return 0;
+		spellers_[lang->lang()] = nullptr;
+		return nullptr;
 	}
 
 	FileName const affix(path + ".aff");
diff --git a/src/Language.cpp b/src/Language.cpp
index 4f625b55b9..84e03b1e9e 100644
--- a/src/Language.cpp
+++ b/src/Language.cpp
@@ -37,10 +37,10 @@ using namespace lyx::support;
 namespace lyx {
 
 Languages languages;
-Language const * ignore_language = 0;
-Language const * default_language = 0;
-Language const * latex_language = 0;
-Language const * reset_language = 0;
+Language const * ignore_language = nullptr;
+Language const * default_language = nullptr;
+Language const * latex_language = nullptr;
+Language const * reset_language = nullptr;
 
 
 bool Language::isPolyglossiaExclusive() const
@@ -344,12 +344,12 @@ void Languages::read(FileName const & filename)
 			break;
 		if (l.lang() == "latex") {
 			// Check if latex language was not already defined.
-			LASSERT(latex_language == 0, continue);
+			LASSERT(latex_language == nullptr, continue);
 			static const Language latex_lang = l;
 			latex_language = &latex_lang;
 		} else if (l.lang() == "ignore") {
 			// Check if ignore language was not already defined.
-			LASSERT(ignore_language == 0, continue);
+			LASSERT(ignore_language == nullptr, continue);
 			static const Language ignore_lang = l;
 			ignore_language = &ignore_lang;
 		} else
@@ -436,7 +436,7 @@ Language const * Languages::getFromCode(string const & code) const
 		if (match(code, l.second) == ApproximateMatch)
 			return &l.second;
 	}
-	return 0;
+	return nullptr;
 }
 
 
@@ -460,7 +460,7 @@ Language const * Languages::getFromCode(string const & code,
 	return getFromCode(code);
 
 	LYXERR0("Unknown language `" << code << "'");
-	return 0;
+	return nullptr;
 }
 
 
diff --git a/src/LyXVC.cpp b/src/LyXVC.cpp
index 806d5e8143..7e36a1ce9c 100644
--- a/src/LyXVC.cpp
+++ b/src/LyXVC.cpp
@@ -348,9 +348,7 @@ string LyXVC::toggleReadOnly()
 
 bool LyXVC::inUse() const
 {
-	if (vcs)
-		return true;
-	return false;
+	return vcs != nullptr;
 }
 
 
diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 242f644ce6..bdda5d012b 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -4810,7 +4810,7 @@ void Paragraph::spellCheck() const
 			// start the spell checker on the unit of meaning
 			docstring word = asString(first, last, AS_STR_INSETS + AS_STR_SKIPDELETE);
 			WordLangTuple wl = WordLangTuple(word, lang);
-			SpellChecker::Result result = word.size() ?
+			SpellChecker::Result result = !word.empty() ?
 				speller->check(wl) : SpellChecker::WORD_OK;
 			d->markMisspelledWords(first, last, result, word, skips);
 			first = ++last;
diff --git a/src/PersonalWordList.cpp b/src/PersonalWordList.cpp
index 665eb331b5..4d3292e3f5 100644
--- a/src/PersonalWordList.cpp
+++ b/src/PersonalWordList.cpp
@@ -54,7 +54,7 @@ void PersonalWordList::load()
 	LYXERR(Debug::FILES, "load personal dictionary from: " << fn);
 	ifstream ifs(fn.toFilesystemEncoding().c_str());
 
-	dirty(words_.size() > 0);
+	dirty(!words_.empty());
 	words_.clear();
 	string line;
 	getline(ifs, line);
diff --git a/src/Session.cpp b/src/Session.cpp
index 3bb9c03a33..8fc8fa23d8 100644
--- a/src/Session.cpp
+++ b/src/Session.cpp
@@ -494,10 +494,7 @@ void AuthFilesSection::write(ostream & os) const
 
 bool AuthFilesSection::find(string const & name) const
 {
-	if (auth_files_.find(name) != auth_files_.end())
-		return true;
-
-	return false;
+	return auth_files_.find(name) != auth_files_.end();
 }
 
 
@@ -547,10 +544,7 @@ bool ShellEscapeSection::find(string const & name) const
 
 bool ShellEscapeSection::findAuth(string const & name) const
 {
-	if (shellescape_files_.find(name + ",1") != shellescape_files_.end())
-		return true;
-
-	return false;
+	return shellescape_files_.find(name + ",1") != shellescape_files_.end();
 }
 
 
diff --git a/src/Text.cpp b/src/Text.cpp
index 0e058641d6..e4eb4abf10 100644
--- a/src/Text.cpp
+++ b/src/Text.cpp
@@ -1778,7 +1778,7 @@ bool Text::backspace(Cursor & cur)
 		Cursor prev_cur = cur;
 		--prev_cur.pit();
 
-		if (cur.paragraph().size() > 0
+		if (!cur.paragraph().empty()
 		    && !prev_cur.paragraph().isMergedOnEndOfParDeletion(cur.buffer()->params().track_changes)) {
 			cur.recordUndo(prev_cur.pit(), prev_cur.pit());
 			prev_cur.paragraph().setChange(prev_cur.lastpos(), Change(Change::DELETED));
diff --git a/src/Text3.cpp b/src/Text3.cpp
index 6631d49012..af904041c2 100644
--- a/src/Text3.cpp
+++ b/src/Text3.cpp
@@ -1276,7 +1276,7 @@ void Text::dispatch(Cursor & cur, FuncRequest & cmd)
 		Paragraph const & nextpar = lastpar ? par : pars_[pit + 1];
 		pit_type prev = pit > 0 ? depthHook(pit, par.getDepth()) : pit;
 		if (prev < pit && cur.pos() == par.beginOfBody()
-		    && !par.size() && !par.isEnvSeparator(cur.pos())
+		    && par.empty() && !par.isEnvSeparator(cur.pos())
 		    && !par.layout().keepempty
 		    && !par.layout().isCommand()
 		    && pars_[prev].layout() != par.layout()
diff --git a/src/TextMetrics.cpp b/src/TextMetrics.cpp
index 8e9a157a7a..07c2b27990 100644
--- a/src/TextMetrics.cpp
+++ b/src/TextMetrics.cpp
@@ -1486,7 +1486,7 @@ InsetList::Element * TextMetrics::checkInsetHit(pit_type pit, int x, int y)
 	}
 
 	LYXERR(Debug::DEBUG, "No inset hit. ");
-	return 0;
+	return nullptr;
 }
 
 
diff --git a/src/Trans.cpp b/src/Trans.cpp
index 679866da84..2f0f317355 100644
--- a/src/Trans.cpp
+++ b/src/Trans.cpp
@@ -510,7 +510,7 @@ docstring const TransDeadkeyState::deadkey(char_type c, KmodInfo d)
 	KmodException::const_iterator cit = deadkey_info_.exception_list.begin();
 	KmodException::const_iterator end = deadkey_info_.exception_list.end();
 	for (; cit != end; ++cit) {
-		if (cit->combined == true && cit->accent == d.accent) {
+		if (cit->combined && cit->accent == d.accent) {
 			deadkey2_ = c;
 			deadkey2_info_ = d;
 			comb_info_ = (*cit);
@@ -656,7 +656,7 @@ void TransManager::deadkey(char_type c, tex_accent accent, Text * t, Cursor & cu
 		// A deadkey was pressed that cannot be printed
 		// or a accent command was typed in the minibuffer
 		KmodInfo i;
-		if (active_->isAccentDefined(accent, i) == true) {
+		if (active_->isAccentDefined(accent, i)) {
 			docstring const res = trans_fsm_
 				.currentState->deadkey(c, i);
 			insert(res, t, cur);
diff --git a/src/VCBackend.cpp b/src/VCBackend.cpp
index 3ea4624399..309d705372 100644
--- a/src/VCBackend.cpp
+++ b/src/VCBackend.cpp
@@ -1156,7 +1156,7 @@ SVN::SVN(FileName const & m, Buffer * b) : VCS(b)
 	// Here we know that the buffer file is either already in SVN or
 	// about to be registered
 	master_ = m;
-	locked_mode_ = 0;
+	locked_mode_ = false;
 	scanMaster();
 }
 
diff --git a/src/frontends/Painter.h b/src/frontends/Painter.h
index 718718f979..e2796d97d9 100644
--- a/src/frontends/Painter.h
+++ b/src/frontends/Painter.h
@@ -154,7 +154,7 @@ public:
 
 	double pixelRatio() const { return pixel_ratio_; }
 
-	double develMode() const { return devel_mode_; }
+	bool develMode() const { return devel_mode_; }
 
 	/// draw the underbar, strikeout, xout, uuline and uwave font attributes
 	virtual void textDecoration(FontInfo const & f, int x, int y, int width) = 0;
diff --git a/src/frontends/qt/CategorizedCombo.cpp b/src/frontends/qt/CategorizedCombo.cpp
index d86bd382f8..4aebcf6a91 100644
--- a/src/frontends/qt/CategorizedCombo.cpp
+++ b/src/frontends/qt/CategorizedCombo.cpp
@@ -71,7 +71,7 @@ private:
 class CCFilterModel : public QSortFilterProxyModel {
 public:
 	///
-	CCFilterModel(QObject * parent = 0)
+	CCFilterModel(QObject * parent = nullptr)
 		: QSortFilterProxyModel(parent)
 	{}
 };
diff --git a/src/frontends/qt/FancyLineEdit.cpp b/src/frontends/qt/FancyLineEdit.cpp
index c7035ac7c9..dae7444899 100644
--- a/src/frontends/qt/FancyLineEdit.cpp
+++ b/src/frontends/qt/FancyLineEdit.cpp
@@ -60,7 +60,7 @@ FancyLineEditPrivate::FancyLineEditPrivate(FancyLineEdit *parent) :
     m_lineEdit(parent)
 {
     for (int i = 0; i < 2; ++i) {
-        m_menu[i] = 0;
+        m_menu[i] = nullptr;
         m_menuTabFocusTrigger[i] = false;
         m_iconbutton[i] = new IconButton(parent);
         m_iconbutton[i]->installEventFilter(this);
diff --git a/src/frontends/qt/FindAndReplace.cpp b/src/frontends/qt/FindAndReplace.cpp
index 271ce9be90..af2bbbbea3 100644
--- a/src/frontends/qt/FindAndReplace.cpp
+++ b/src/frontends/qt/FindAndReplace.cpp
@@ -599,7 +599,7 @@ FindAndReplace::FindAndReplace(GuiView & parent,
 
 FindAndReplace::~FindAndReplace()
 {
-	setFocusProxy(0);
+	setFocusProxy(nullptr);
 	delete widget_;
 }
 
@@ -620,7 +620,7 @@ void FindAndReplaceWidget::updateGUI()
 				old_buffer_ = &bv->buffer();
 		}
 	} else
-		old_buffer_ = 0;
+		old_buffer_ = nullptr;
 
 	bool const replace_enabled = bv && !bv->buffer().isReadonly();
 	replace_work_area_->setEnabled(replace_enabled);
diff --git a/src/frontends/qt/FloatPlacement.cpp b/src/frontends/qt/FloatPlacement.cpp
index dbbaa5961b..d11458716f 100644
--- a/src/frontends/qt/FloatPlacement.cpp
+++ b/src/frontends/qt/FloatPlacement.cpp
@@ -35,7 +35,7 @@ namespace frontend {
 
 FloatPlacement::FloatPlacement(bool show_options, QWidget * parent)
 	: InsetParamsWidget(parent), standardfloat_(true),
-	  allows_wide_(true), allows_sideways_(true), float_list_(0)
+	  allows_wide_(true), allows_sideways_(true), float_list_(nullptr)
 {
 	setupUi(this);
 
diff --git a/src/frontends/qt/GuiApplication.cpp b/src/frontends/qt/GuiApplication.cpp
index bf91789178..1763abdfc0 100644
--- a/src/frontends/qt/GuiApplication.cpp
+++ b/src/frontends/qt/GuiApplication.cpp
@@ -895,8 +895,8 @@ public:
 
 struct GuiApplication::Private
 {
-	Private(): language_model_(0), meta_fake_bit(NoModifier),
-		global_menubar_(0)
+	Private(): language_model_(nullptr), meta_fake_bit(NoModifier),
+		global_menubar_(nullptr)
 	{
 	#if (QT_VERSION < 0x050000) || (QT_VERSION >= 0x050400)
 	#if defined(Q_OS_WIN) || defined(Q_CYGWIN_WIN)
@@ -993,7 +993,7 @@ GuiApplication::~GuiApplication()
 
 
 GuiApplication::GuiApplication(int & argc, char ** argv)
-	: QApplication(argc, argv), current_view_(0),
+	: QApplication(argc, argv), current_view_(nullptr),
 	  d(new GuiApplication::Private)
 {
 	QString app_name = "LyX";
@@ -1123,8 +1123,8 @@ FuncStatus GuiApplication::getStatus(FuncRequest const & cmd) const
 {
 	FuncStatus status;
 
-	BufferView * bv = 0;
-	BufferView * doc_bv = 0;
+	BufferView * bv = nullptr;
+	BufferView * doc_bv = nullptr;
 
 	if (cmd.action() == LFUN_NOACTION) {
 		status.message(from_utf8(N_("Nothing to do")));
@@ -1289,7 +1289,7 @@ bool GuiApplication::getStatus(FuncRequest const & cmd, FuncStatus & flag) const
 		break;
 
 	case LFUN_WINDOW_CLOSE:
-		enable = d->views_.size() > 0;
+		enable = !d->views_.empty();
 		break;
 
 	case LFUN_BUFFER_NEW:
diff --git a/src/frontends/qt/GuiErrorList.cpp b/src/frontends/qt/GuiErrorList.cpp
index 0b625ccd51..9fbdedafaf 100644
--- a/src/frontends/qt/GuiErrorList.cpp
+++ b/src/frontends/qt/GuiErrorList.cpp
@@ -58,7 +58,7 @@ namespace lyx {
 namespace frontend {
 
 GuiErrorList::GuiErrorList(GuiView & lv)
-	: GuiDialog(lv, "errorlist", qt_("Error List")), buf_(0), from_master_(false)
+	: GuiDialog(lv, "errorlist", qt_("Error List")), buf_(nullptr), from_master_(false)
 {
 	setupUi(this);
 
diff --git a/src/frontends/qt/GuiImage.cpp b/src/frontends/qt/GuiImage.cpp
index c73fe7cede..0c3df0b65d 100644
--- a/src/frontends/qt/GuiImage.cpp
+++ b/src/frontends/qt/GuiImage.cpp
@@ -173,7 +173,7 @@ bool GuiImage::clip(Params const & params)
 
 bool GuiImage::rotate(Params const & params)
 {
-	if (!params.angle)
+	if (params.angle == 0)
 		return false;
 
 	QImage const & image = is_transformed_ ? transformed_ : original_;
diff --git a/src/frontends/qt/GuiRef.cpp b/src/frontends/qt/GuiRef.cpp
index a727700005..8583d0cd26 100644
--- a/src/frontends/qt/GuiRef.cpp
+++ b/src/frontends/qt/GuiRef.cpp
@@ -187,7 +187,6 @@ void GuiRef::selectionChanged()
 		return;
 	QTreeWidgetItem * sel = selections.first();
 	refHighlighted(sel);
-	return;
 }
 
 
diff --git a/src/frontends/qt/GuiSendto.cpp b/src/frontends/qt/GuiSendto.cpp
index a42bbb472c..b14db45304 100644
--- a/src/frontends/qt/GuiSendto.cpp
+++ b/src/frontends/qt/GuiSendto.cpp
@@ -38,7 +38,7 @@ namespace frontend {
 
 
 GuiSendTo::GuiSendTo(GuiView & lv)
-	: GuiDialog(lv, "sendto", qt_("Export or Send Document")), format_(0)
+	: GuiDialog(lv, "sendto", qt_("Export or Send Document")), format_(nullptr)
 {
 	setupUi(this);
 
@@ -77,7 +77,7 @@ void GuiSendTo::updateContents()
 	Format const * current_format = nullptr;
 	int const line = formatLW->currentRow();
 	if (line >= 0 && static_cast<unsigned int>(line) < all_formats.size()
-	    && formatLW->selectedItems().size() > 0)
+	    && !formatLW->selectedItems().empty())
 		current_format = all_formats[line];
 	// Reset the list widget
 	formatLW->clear();
@@ -115,14 +115,14 @@ bool GuiSendTo::isValid()
 	if (line < 0 || (line > int(formatLW->count())))
 		return false;
 
-	return (formatLW->selectedItems().size() > 0
+	return (!formatLW->selectedItems().empty()
 		&& formatLW->count() != 0);
 }
 
 
 bool GuiSendTo::initialiseParams(string const &)
 {
-	format_ = 0;
+	format_ = nullptr;
 	paramsToDialog(format_, command_);
 	return true;
 }
diff --git a/src/frontends/qt/GuiSymbols.cpp b/src/frontends/qt/GuiSymbols.cpp
index a4fd4af650..4a6b0d6178 100644
--- a/src/frontends/qt/GuiSymbols.cpp
+++ b/src/frontends/qt/GuiSymbols.cpp
@@ -207,7 +207,7 @@ class GuiSymbols::Model : public QAbstractListModel
 {
 public:
 	Model(GuiSymbols * parent)
-		: QAbstractListModel(parent), encoding_(0)
+		: QAbstractListModel(parent), encoding_(nullptr)
 	{}
 
 	QModelIndex index(int row, int column, QModelIndex const &) const override
diff --git a/src/frontends/qt/GuiToolbar.cpp b/src/frontends/qt/GuiToolbar.cpp
index 65f81c9b21..5c8c603daf 100644
--- a/src/frontends/qt/GuiToolbar.cpp
+++ b/src/frontends/qt/GuiToolbar.cpp
@@ -64,7 +64,7 @@ namespace frontend {
 
 GuiToolbar::GuiToolbar(ToolbarInfo const & tbinfo, GuiView & owner)
 	: QToolBar(toqstr(tbinfo.gui_name), &owner), visibility_(0),
-	  owner_(owner), command_buffer_(0), tbinfo_(tbinfo), filled_(false),
+	  owner_(owner), command_buffer_(nullptr), tbinfo_(tbinfo), filled_(false),
 	  restored_(false)
 {
 	setIconSize(owner.iconSize());
@@ -297,7 +297,7 @@ class DynamicMenuButton::Private
 	Private(Private const &);
 	void operator=(Private const &);
 public:
-	Private() : inset_(0) {}
+	Private() : inset_(nullptr) {}
 	///
 	DocumentClassConstPtr text_class_;
 	///
diff --git a/src/frontends/qt/GuiView.cpp b/src/frontends/qt/GuiView.cpp
index cb351d1177..00f3b96ea4 100644
--- a/src/frontends/qt/GuiView.cpp
+++ b/src/frontends/qt/GuiView.cpp
@@ -1187,7 +1187,7 @@ void GuiView::dropEvent(QDropEvent * event)
 				found_formats.push_back(*it);
 
 		FuncRequest cmd;
-		if (found_formats.size() >= 1) {
+		if (!found_formats.empty()) {
 			if (found_formats.size() > 1) {
 				//FIXME: show a dialog to choose the correct importable format
 				LYXERR(Debug::FILES,
diff --git a/src/frontends/qt/GuiWorkArea.cpp b/src/frontends/qt/GuiWorkArea.cpp
index 7c21088643..0104c8dd83 100644
--- a/src/frontends/qt/GuiWorkArea.cpp
+++ b/src/frontends/qt/GuiWorkArea.cpp
@@ -1061,7 +1061,6 @@ void GuiWorkArea::generateSyntheticMouseEvent()
 	cur.boundary(bound);
 
 	d->buffer_view_->buffer().changed(false);
-	return;
 }
 
 
diff --git a/src/frontends/qt/LayoutBox.cpp b/src/frontends/qt/LayoutBox.cpp
index 95814c942f..719a2d324d 100644
--- a/src/frontends/qt/LayoutBox.cpp
+++ b/src/frontends/qt/LayoutBox.cpp
@@ -85,7 +85,7 @@ private:
 class GuiLayoutFilterModel : public QSortFilterProxyModel {
 public:
 	///
-	GuiLayoutFilterModel(QObject * parent = 0)
+	GuiLayoutFilterModel(QObject * parent = nullptr)
 		: QSortFilterProxyModel(parent)
 	{}
 
@@ -111,7 +111,7 @@ class LayoutBox::Private
 	void operator=(Private const &);
 public:
 	Private(LayoutBox * parent, GuiView & gv) : p(parent), owner_(gv),
-		inset_(0),
+		inset_(nullptr),
 		// set the layout model with two columns
 		// 1st: translated layout names
 		// 2nd: raw layout names
@@ -567,7 +567,7 @@ void LayoutBox::updateContents(bool reset)
 		setEnabled(false);
 		setMinimumWidth(sizeHint().width());
 		d->text_class_.reset();
-		d->inset_ = 0;
+		d->inset_ = nullptr;
 		return;
 	}
 	// we'll only update the layout list if the text class has changed
diff --git a/src/frontends/qt/PanelStack.cpp b/src/frontends/qt/PanelStack.cpp
index 4b6b875c8b..ef9c599a34 100644
--- a/src/frontends/qt/PanelStack.cpp
+++ b/src/frontends/qt/PanelStack.cpp
@@ -97,7 +97,7 @@ PanelStack::PanelStack(QWidget * parent)
 
 void PanelStack::addCategory(QString const & name, QString const & parent)
 {
-	QTreeWidgetItem * item = 0;
+	QTreeWidgetItem * item = nullptr;
 
 	LYXERR(Debug::GUI, "addCategory n= " << name << "   parent= ");
 
diff --git a/src/frontends/qt/Toolbars.cpp b/src/frontends/qt/Toolbars.cpp
index d7a28b8025..7d29344732 100644
--- a/src/frontends/qt/Toolbars.cpp
+++ b/src/frontends/qt/Toolbars.cpp
@@ -418,7 +418,7 @@ ToolbarInfo const * Toolbars::info(std::string const & name) const
 	for (Infos::const_iterator it = toolbar_info_.begin(); it != end; ++it)
 		if (it->name == name)
 			return &(*it);
-	return 0;
+	return nullptr;
 }
 
 
diff --git a/src/insets/InsetIPAMacro.cpp b/src/insets/InsetIPAMacro.cpp
index 4e8afcfa7e..82f6c48e84 100644
--- a/src/insets/InsetIPAMacro.cpp
+++ b/src/insets/InsetIPAMacro.cpp
@@ -393,7 +393,7 @@ bool InsetIPADeco::insetAllowed(InsetCode code) const
 
 
 InsetIPAChar::InsetIPAChar(Kind k)
-	: Inset(0), kind_(k)
+	: Inset(nullptr), kind_(k)
 {}
 
 
diff --git a/src/insets/InsetNewline.cpp b/src/insets/InsetNewline.cpp
index 4c6f17e1d1..0e07af13f7 100644
--- a/src/insets/InsetNewline.cpp
+++ b/src/insets/InsetNewline.cpp
@@ -36,7 +36,7 @@ using namespace std;
 
 namespace lyx {
 
-InsetNewline::InsetNewline() : Inset(0)
+InsetNewline::InsetNewline() : Inset(nullptr)
 {}
 
 
diff --git a/src/insets/InsetNewpage.cpp b/src/insets/InsetNewpage.cpp
index 6e9f34211f..6f89eac03b 100644
--- a/src/insets/InsetNewpage.cpp
+++ b/src/insets/InsetNewpage.cpp
@@ -37,12 +37,12 @@ using namespace std;
 
 namespace lyx {
 
-	InsetNewpage::InsetNewpage() : Inset(0)
+	InsetNewpage::InsetNewpage() : Inset(nullptr)
 {}
 
 
 InsetNewpage::InsetNewpage(InsetNewpageParams const & params)
-	: Inset(0), params_(params)
+	: Inset(nullptr), params_(params)
 {}
 
 
diff --git a/src/insets/InsetNomencl.cpp b/src/insets/InsetNomencl.cpp
index c762e33d67..5e3c637a60 100644
--- a/src/insets/InsetNomencl.cpp
+++ b/src/insets/InsetNomencl.cpp
@@ -171,7 +171,7 @@ docstring InsetPrintNomencl::screenLabel() const
 
 
 struct NomenclEntry {
-	NomenclEntry() : par(0) {}
+	NomenclEntry() : par(nullptr) {}
 	NomenclEntry(docstring s, docstring d, Paragraph const * p)
 	  : symbol(s), desc(d), par(p)
 	{}
@@ -381,7 +381,7 @@ docstring nomenclWidest(Buffer const & buffer, OutputParams const & runparams)
 
 	int w = 0;
 	docstring symb;
-	InsetNomencl const * nomencl = 0;
+	InsetNomencl const * nomencl = nullptr;
 	ParagraphList::const_iterator it = buffer.paragraphs().begin();
 	ParagraphList::const_iterator end = buffer.paragraphs().end();
 
diff --git a/src/insets/InsetQuotes.cpp b/src/insets/InsetQuotes.cpp
index b90f1c27dd..c93de5a063 100644
--- a/src/insets/InsetQuotes.cpp
+++ b/src/insets/InsetQuotes.cpp
@@ -1057,10 +1057,10 @@ void InsetQuotes::validate(LaTeXFeatures & features) const
 	switch (type) {
 	case 0x0027: {
 		if (features.runparams().isFullUnicode() && fontspec_)
-				features.require("textquotesinglep");
-			else
-				features.require("textcomp");
-			break;
+			features.require("textquotesinglep");
+		else
+			features.require("textcomp");
+		break;
 	}
 	case 0x0022: {
 		if (features.runparams().isFullUnicode() && fontspec_)
diff --git a/src/insets/InsetSeparator.cpp b/src/insets/InsetSeparator.cpp
index efe6a483b0..16f7cdcbdf 100644
--- a/src/insets/InsetSeparator.cpp
+++ b/src/insets/InsetSeparator.cpp
@@ -36,12 +36,12 @@ using namespace lyx::frontend;
 
 namespace lyx {
 
-InsetSeparator::InsetSeparator() : Inset(0)
+InsetSeparator::InsetSeparator() : Inset(nullptr)
 {}
 
 
 InsetSeparator::InsetSeparator(InsetSeparatorParams const & params)
-	: Inset(0), params_(params)
+	: Inset(nullptr), params_(params)
 {}
 
 
diff --git a/src/insets/InsetSpace.cpp b/src/insets/InsetSpace.cpp
index 7656a14e10..d4cb7361b4 100644
--- a/src/insets/InsetSpace.cpp
+++ b/src/insets/InsetSpace.cpp
@@ -45,7 +45,7 @@ namespace lyx {
 
 
 InsetSpace::InsetSpace(InsetSpaceParams const & params)
-	: Inset(0), params_(params)
+	: Inset(nullptr), params_(params)
 {}
 
 
diff --git a/src/insets/InsetSpecialChar.cpp b/src/insets/InsetSpecialChar.cpp
index 56925c4f32..3ecdaf12e9 100644
--- a/src/insets/InsetSpecialChar.cpp
+++ b/src/insets/InsetSpecialChar.cpp
@@ -38,7 +38,7 @@ namespace lyx {
 
 
 InsetSpecialChar::InsetSpecialChar(Kind k)
-	: Inset(0), kind_(k)
+	: Inset(nullptr), kind_(k)
 {}
 
 
diff --git a/src/insets/InsetTabular.cpp b/src/insets/InsetTabular.cpp
index 8458ce4728..d24d174cbc 100644
--- a/src/insets/InsetTabular.cpp
+++ b/src/insets/InsetTabular.cpp
@@ -2189,9 +2189,7 @@ bool Tabular::needRotating() const
 
 bool Tabular::isLastCell(idx_type cell) const
 {
-	if (cell + 1 < numberofcells)
-		return false;
-	return true;
+	return cell + 1 >= numberofcells;
 }
 
 
diff --git a/src/insets/InsetVSpace.cpp b/src/insets/InsetVSpace.cpp
index a6092cb8a3..03a272e650 100644
--- a/src/insets/InsetVSpace.cpp
+++ b/src/insets/InsetVSpace.cpp
@@ -50,7 +50,7 @@ int const ADD_TO_VSPACE_WIDTH = 5;
 
 
 InsetVSpace::InsetVSpace(VSpace const & space)
-	: Inset(0), space_(space)
+	: Inset(nullptr), space_(space)
 {}
 
 
diff --git a/src/lyxfind.cpp b/src/lyxfind.cpp
index 5f9e2d3093..f36e02bf77 100644
--- a/src/lyxfind.cpp
+++ b/src/lyxfind.cpp
@@ -360,7 +360,7 @@ pair<bool, int> replaceOne(BufferView * bv, docstring searchstr,
 	if (!cur.selection()) {
 		// no selection, non-empty search string: find it
 		if (!searchstr.empty()) {
-			bool found = findOne(bv, searchstr, case_sens, whole, forward, true, findnext);
+			bool const found = findOne(bv, searchstr, case_sens, whole, forward, true, findnext);
 			return make_pair(found, 0);
 		}
 		// empty search string
@@ -389,7 +389,7 @@ pair<bool, int> replaceOne(BufferView * bv, docstring searchstr,
 	// no selection or current selection is not search word:
 	// just find the search word
 	if (!have_selection || !match) {
-		bool found = findOne(bv, searchstr, case_sens, whole, forward, true, findnext);
+		bool const found = findOne(bv, searchstr, case_sens, whole, forward, true, findnext);
 		return make_pair(found, 0);
 	}
 
@@ -3592,7 +3592,7 @@ static bool firstUppercase(Cursor const & cur)
 static void changeFirstCase(Buffer & buffer, TextCase first_case, TextCase others_case)
 {
 	ParagraphList::iterator pit = buffer.paragraphs().begin();
-	LASSERT(pit->size() >= 1, /**/);
+	LASSERT(!pit->empty(), /**/);
 	pos_type right = pos_type(1);
 	pit->changeCase(buffer.params(), pos_type(0), right, first_case);
 	right = pit->size();
@@ -3605,7 +3605,7 @@ static void changeFirstCase(Buffer & buffer, TextCase first_case, TextCase other
 static int findAdvReplace(BufferView * bv, FindAndReplaceOptions const & opt, MatchStringAdv & matchAdv)
 {
 	Cursor & cur = bv->cursor();
-	if (opt.repl_buf_name == docstring()
+	if (opt.repl_buf_name.empty()
 	    || theBufferList().getBuffer(FileName(to_utf8(opt.repl_buf_name)), true) == 0
 	    || theBufferList().getBuffer(FileName(to_utf8(opt.find_buf_name)), true) == 0)
 		return 0;
diff --git a/src/mathed/InsetMathColor.cpp b/src/mathed/InsetMathColor.cpp
index 94a6c42e64..31ba778faf 100644
--- a/src/mathed/InsetMathColor.cpp
+++ b/src/mathed/InsetMathColor.cpp
@@ -99,10 +99,10 @@ void InsetMathColor::write(WriteStream & os) const
 	// We have to ensure correct spacing when the front and/or back
 	// atoms are not ordinary ones (bug 11827).
 	docstring const frontclass =
-		cell(0).size() ? class_to_string(cell(0).front()->mathClass())
+		!cell(0).empty() ? class_to_string(cell(0).front()->mathClass())
 		               : from_ascii("mathord");
 	docstring const backclass =
-		cell(0).size() ? class_to_string(cell(0).back()->mathClass())
+		!cell(0).empty() ? class_to_string(cell(0).back()->mathClass())
 		               : from_ascii("mathord");
 	bool adjchk = os.latex() && !os.inMathClass() && (normalcolor(color_) || oldstyle_);
 	bool adjust_front = frontclass != "mathord" && adjchk;
diff --git a/src/mathed/InsetMathFont.cpp b/src/mathed/InsetMathFont.cpp
index f199ee5bcf..1de00464a7 100644
--- a/src/mathed/InsetMathFont.cpp
+++ b/src/mathed/InsetMathFont.cpp
@@ -58,9 +58,7 @@ InsetMath::mode_type InsetMathFont::currentMode() const
 
 bool InsetMathFont::lockedMode() const
 {
-	if (key_->extra == "forcetext")
-		return true;
-	return false;
+	return key_->extra == "forcetext";
 }
 
 
diff --git a/src/mathed/InsetMathFrac.cpp b/src/mathed/InsetMathFrac.cpp
index 90d507cfbe..03125e99ca 100644
--- a/src/mathed/InsetMathFrac.cpp
+++ b/src/mathed/InsetMathFrac.cpp
@@ -80,13 +80,13 @@ Inset * InsetMathFrac::clone() const
 
 InsetMathFrac * InsetMathFrac::asFracInset()
 {
-	return kind_ == ATOP ? 0 : this;
+	return kind_ == ATOP ? nullptr : this;
 }
 
 
 InsetMathFrac const * InsetMathFrac::asFracInset() const
 {
-	return kind_ == ATOP ? 0 : this;
+	return kind_ == ATOP ? nullptr : this;
 }
 
 
diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index e7326b64e5..156cbec2fd 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -1579,7 +1579,7 @@ void InsetMathHull::mutate(HullType newtype)
 			numbered(0, false);
 		} else {
 			setType(hullEquation);
-			numbered(0, label_[0] ? true : false);
+			numbered(0, label_[0] != nullptr);
 			mutate(newtype);
 		}
 		break;
diff --git a/src/mathed/InsetMathMacro.cpp b/src/mathed/InsetMathMacro.cpp
index 15b5d29d9c..862ee8a4d7 100644
--- a/src/mathed/InsetMathMacro.cpp
+++ b/src/mathed/InsetMathMacro.cpp
@@ -205,7 +205,7 @@ public:
 		: name_(name), displayMode_(DISPLAY_INIT),
 		  expanded_(buf), definition_(buf), attachedArgsNum_(0),
 		  optionals_(0), nextFoldMode_(true), macroBackup_(buf),
-		  macro_(0), needsUpdate_(false), isUpdating_(false),
+		  macro_(nullptr), needsUpdate_(false), isUpdating_(false),
 		  appetite_(9), nesting_(0), limits_(AUTO_LIMITS)
 	{
 	}
@@ -649,7 +649,7 @@ void InsetMathMacro::updateMacro(MacroContext const & mc)
 			d->needsUpdate_ = true;
 		}
 	} else {
-		d->macro_ = 0;
+		d->macro_ = nullptr;
 	}
 }
 
@@ -684,7 +684,7 @@ void InsetMathMacro::updateRepresentation(Cursor * cur, MacroContext const & mc,
 	UpdateLocker locker(*this);
 
 	// known macro?
-	if (d->macro_ == 0)
+	if (d->macro_ == nullptr)
 		return;
 
 	// remember nesting level of this macro
@@ -837,7 +837,7 @@ void InsetMathMacro::setDisplayMode(InsetMathMacro::DisplayMode mode, int appeti
 
 InsetMathMacro::DisplayMode InsetMathMacro::computeDisplayMode() const
 {
-	if (d->nextFoldMode_ == true && d->macro_ && !d->macro_->locked())
+	if (d->nextFoldMode_ && d->macro_ && !d->macro_->locked())
 		return DISPLAY_NORMAL;
 	else
 		return DISPLAY_UNFOLDED;
@@ -1172,10 +1172,10 @@ void InsetMathMacro::write(WriteStream & os) const
 		// contains macros with optionals.
 		bool braced = false;
 		size_type last = cell(i).size() - 1;
-		if (cell(i).size() && cell(i)[last]->asUnknownInset()) {
+		if (!cell(i).empty() && cell(i)[last]->asUnknownInset()) {
 			latexkeys const * l = in_word_set(cell(i)[last]->name());
 			braced = (l && l->inset == "big");
-		} else if (cell(i).size() && cell(i)[0]->asScriptInset()) {
+		} else if (!cell(i).empty() && cell(i)[0]->asScriptInset()) {
 			braced = cell(i)[0]->asScriptInset()->nuc().empty();
 		} else {
 			for (size_type j = 0; j < cell(i).size(); ++j) {
diff --git a/src/mathed/InsetMathNest.cpp b/src/mathed/InsetMathNest.cpp
index be6fecc526..9d88b1337b 100644
--- a/src/mathed/InsetMathNest.cpp
+++ b/src/mathed/InsetMathNest.cpp
@@ -2027,7 +2027,7 @@ CompletionList const *
 InsetMathNest::createCompletionList(Cursor const & cur) const
 {
 	if (!cur.inMacroMode())
-		return 0;
+		return nullptr;
 
 	return new MathCompletionList(cur);
 }
diff --git a/src/mathed/InsetMathScript.cpp b/src/mathed/InsetMathScript.cpp
index cbef2fafb1..e40db4f164 100644
--- a/src/mathed/InsetMathScript.cpp
+++ b/src/mathed/InsetMathScript.cpp
@@ -388,7 +388,7 @@ void InsetMathScript::removeScript(bool up)
 		if (up == cell_1_is_up_)
 			cells_.pop_back();
 	} else if (nargs() == 3) {
-		if (up == true) {
+		if (up) {
 			swap(cells_[1], cells_[2]);
 			cell_1_is_up_ = false;
 		} else {
diff --git a/src/mathed/MathExtern.cpp b/src/mathed/MathExtern.cpp
index 18340e11c8..092de56ee5 100644
--- a/src/mathed/MathExtern.cpp
+++ b/src/mathed/MathExtern.cpp
@@ -75,7 +75,7 @@ static char const * function_names[] = {
 	"det", "dim", "exp", "gcd", "hom", "inf", "ker",
 	"lg", "lim", "liminf", "limsup", "ln", "log",
 	"max", "min", "sec", "sin", "sinh", "sup",
-	"tan", "tanh", "Pr", 0
+	"tan", "tanh", "Pr", nullptr
 };
 
 static size_t const npos = lyx::docstring::npos;
diff --git a/src/mathed/MathFactory.cpp b/src/mathed/MathFactory.cpp
index afee57ef1c..54fe012857 100644
--- a/src/mathed/MathFactory.cpp
+++ b/src/mathed/MathFactory.cpp
@@ -444,9 +444,9 @@ latexkeys const * in_word_set(docstring const & str)
 {
 	MathWordList::iterator it = theMathWordList.find(str);
 	if (it == theMathWordList.end())
-		return 0;
+		return nullptr;
 	if (it->second.inset == "macro")
-		return 0;
+		return nullptr;
 	return &(it->second);
 }
 
diff --git a/src/mathed/MathParser.cpp b/src/mathed/MathParser.cpp
index c3bea0d540..32d7ef6424 100644
--- a/src/mathed/MathParser.cpp
+++ b/src/mathed/MathParser.cpp
@@ -1497,7 +1497,7 @@ bool Parser::parse1(InsetMathGrid & grid, unsigned flags,
 				if (ar[i].size() == 1)
 					script[i] = ar[i][0].nucleus()->asScriptInset();
 			}
-			bool const hasscript[2] = {script[0] ? true : false, script[1] ? true : false};
+			bool const hasscript[2] = {script[0] != nullptr, script[1] != nullptr};
 			cell->push_back(MathAtom(new InsetMathSideset(buf, hasscript[0], hasscript[1])));
 			if (hasscript[0]) {
 				if (script[0]->hasDown())
diff --git a/src/mathed/MathRow.cpp b/src/mathed/MathRow.cpp
index d78815acf3..be61c8a39c 100644
--- a/src/mathed/MathRow.cpp
+++ b/src/mathed/MathRow.cpp
@@ -39,7 +39,7 @@ namespace lyx {
 
 MathRow::Element::Element(MetricsInfo const & mi, Type t, MathClass mc)
 	: type(t), mclass(mc), before(0), after(0), macro_nesting(mi.base.macro_nesting),
-	  marker(InsetMath::NO_MARKER), inset(0), compl_unique_to(0), ar(0),
+	  marker(InsetMath::NO_MARKER), inset(nullptr), compl_unique_to(0), ar(nullptr),
 	  color(Color_red)
 {}
 
diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index fefa62fa10..b2d51488cd 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -109,7 +109,7 @@ bool atSameLastLangSwitchDepth(OutputState const * state)
 	// commands. Instead, return always true when using babel with
 	// only a begin command.
 
-	return state->lang_switch_depth_.size() == 0
+	return state->lang_switch_depth_.empty()
 			? true
 			: abs(state->lang_switch_depth_.top()) == state->nest_level_;
 }
@@ -119,7 +119,7 @@ bool isLocalSwitch(OutputState const * state)
 {
 	// Return true if the language was opened by a local command switch.
 
-	return state->lang_switch_depth_.size()
+	return !state->lang_switch_depth_.empty()
 		&& state->lang_switch_depth_.top() < 0;
 }
 
@@ -128,7 +128,7 @@ bool langOpenedAtThisLevel(OutputState const * state)
 {
 	// Return true if the language was opened at the current nesting level.
 
-	return state->lang_switch_depth_.size()
+	return !state->lang_switch_depth_.empty()
 		&& abs(state->lang_switch_depth_.top()) == state->nest_level_;
 }
 
@@ -241,7 +241,7 @@ static TeXEnvironmentData prepareEnvironment(Buffer const & buf,
 		// polyglossia or begin/end commands, then the current
 		// language is the document language.
 		string const & cur_lang = using_begin_end
-					  && state->lang_switch_depth_.size()
+					  && !state->lang_switch_depth_.empty()
 						  ? openLanguageName(state)
 						  : doc_lang;
 
@@ -442,7 +442,7 @@ void TeXEnvironment(Buffer const & buf, Text const & text,
 			if ((par->layout() != nextpar->layout()
 			     || par->params().depth() == nextpar->params().depth()
 			     || par->params().leftIndent() == nextpar->params().leftIndent())
-			    && !runparams.for_search && cpar.size() > 0
+			    && !runparams.for_search && !cpar.empty()
 			    && cpar.isDeleted(0, cpar.size()) && !buf.params().output_changes) {
 				if (!buf.params().output_changes && !cpar.parEndChange().deleted())
 					os << '\n' << '\n';
@@ -761,7 +761,7 @@ void TeXOnePar(Buffer const & buf,
 	// Do not output empty commands if the whole paragraph has
 	// been deleted with ct and changes are not output.
 	if (!runparams_in.for_search && style.latextype != LATEX_ENVIRONMENT
-	    && par.size() > 0 && par.isDeleted(0, par.size()) && !bparams.output_changes)
+	    && !par.empty() && par.isDeleted(0, par.size()) && !bparams.output_changes)
 		return;
 
 	LYXERR(Debug::LATEX, "TeXOnePar for paragraph " << pit << " ptr " << &par << " '"
@@ -1312,7 +1312,7 @@ void TeXOnePar(Buffer const & buf,
 						&& nextpar
 						&& style != nextpar->layout())))
 				    || (atSameLastLangSwitchDepth(state)
-					&& state->lang_switch_depth_.size()
+					&& !state->lang_switch_depth_.empty()
 					&& cur_lang != par_lang)
 				    || in_polyglossia_rtl_env)
 				{
@@ -1355,7 +1355,7 @@ void TeXOnePar(Buffer const & buf,
 	}
 
 	bool const last_was_separator =
-		par.size() > 0 && par.isEnvSeparator(par.size() - 1);
+		!par.empty() && par.isEnvSeparator(par.size() - 1);
 
 	// Signify added/deleted par break in output if show changes in output
 	if (nextpar && !os.afterParbreak() && !last_was_separator
@@ -1666,7 +1666,7 @@ void latexParagraphs(Buffer const & buf,
 			if ((par->layout() != nextpar->layout()
 			     || par->params().depth() == nextpar->params().depth()
 			     || par->params().leftIndent() == nextpar->params().leftIndent())
-			    && !runparams.for_search && cpar.size() > 0
+			    && !runparams.for_search && !cpar.empty()
 			    && cpar.isDeleted(0, cpar.size()) && !bparams.output_changes) {
 				if (!cpar.parEndChange().deleted())
 					os << '\n' << '\n';
diff --git a/src/support/FileName.cpp b/src/support/FileName.cpp
index a6b849407a..9714965bdf 100644
--- a/src/support/FileName.cpp
+++ b/src/support/FileName.cpp
@@ -89,7 +89,7 @@ struct FileName::Private
 		: fi(toqstr(handleTildeName(abs_filename)))
 	{
 		name = fromqstr(fi.absoluteFilePath());
-		fi.setCaching(fi.exists() ? true : false);
+		fi.setCaching(fi.exists());
 	}
 	///
 	inline void refresh()
diff --git a/src/support/Package.cpp b/src/support/Package.cpp
index f931ddf705..a349a5e755 100644
--- a/src/support/Package.cpp
+++ b/src/support/Package.cpp
@@ -366,10 +366,7 @@ bool inBuildDir(FileName const & abs_binary,
 bool doesFileExist(FileName & result, string const & search_dir, string const & name)
 {
     result = fileSearch(search_dir, name);
-    if (!result.empty()) {
-        return true;
-    }
-    return false;
+    return !result.empty();
 }
 
 
@@ -382,7 +379,7 @@ bool lyxBinaryPath(FileName & lyx_binary, string const & search_dir, string cons
     } else if (doesFileExist(lyx_binary, search_dir, "lyx" + string(PROGRAM_SUFFIX) + ext)) {
     } else if (doesFileExist(lyx_binary, search_dir, "LyX" + string(PROGRAM_SUFFIX) + ext)){
     }
-    return !lyx_binary.empty() ? true : false;
+    return !lyx_binary.empty();
 }
 
 
diff --git a/src/support/docstring.cpp b/src/support/docstring.cpp
index e73c3f09c0..cbee18a20a 100644
--- a/src/support/docstring.cpp
+++ b/src/support/docstring.cpp
@@ -625,7 +625,7 @@ protected:
 			}
 			if (ok) {
 				err = ios_base::goodbit;
-				v = truename == s ? true : false;
+				v = (truename == s);
 			} else
 				err = ios_base::failbit;
 			if (iit == eit)
diff --git a/src/tests/check_layout.cpp b/src/tests/check_layout.cpp
index 7100c712d8..2fa0fe11e9 100644
--- a/src/tests/check_layout.cpp
+++ b/src/tests/check_layout.cpp
@@ -57,7 +57,7 @@ bool test_Layout(string const & input, string const & output)
 		return false;
 	}
 	LayoutFile const & f = l[i];
-	ostream * os = NULL;
+	ostream * os = nullptr;
 	if (output == "-")
 		os = &cout;
 	else if (!output.empty())
diff --git a/src/tex2lyx/Parser.cpp b/src/tex2lyx/Parser.cpp
index cc8dd5aa58..e44aa3e69a 100644
--- a/src/tex2lyx/Parser.cpp
+++ b/src/tex2lyx/Parser.cpp
@@ -154,7 +154,7 @@ iparserdocstream & iparserdocstream::get(char_type &c)
 
 
 Parser::Parser(idocstream & is, std::string const & fixedenc)
-	: lineno_(0), pos_(0), iss_(0), is_(is),
+	: lineno_(0), pos_(0), iss_(nullptr), is_(is),
 	  encoding_iconv_(fixedenc.empty() ? "UTF-8" : fixedenc),
 	  theCatcodesType_(NORMAL_CATCODES), curr_cat_(UNDECIDED_CATCODES),
 	  fixed_enc_(!fixedenc.empty())