diff --git a/api/logic/Commandline.cpp b/api/logic/Commandline.cpp
index 32a605d6..751182af 100644
--- a/api/logic/Commandline.cpp
+++ b/api/logic/Commandline.cpp
@@ -44,7 +44,7 @@ QStringList splitArgs(QString args)
 		}
 		else if (!inquotes.isNull())
 		{
-			if (cchar == 0x5C)
+			if (cchar == '\\')
 				escape = true;
 			else if (cchar == inquotes)
 				inquotes = 0;
@@ -54,7 +54,7 @@ QStringList splitArgs(QString args)
 		}
 		else
 		{
-			if (cchar == 0x20)
+			if (cchar == ' ')
 			{
 				if (!current.isEmpty())
 				{
@@ -62,7 +62,7 @@ QStringList splitArgs(QString args)
 					current.clear();
 				}
 			}
-			else if (cchar == 0x22 || cchar == 0x27)
+			else if (cchar == '"' || cchar == '\'')
 				inquotes = cchar;
 			else
 				current += cchar;
diff --git a/api/logic/minecraft/ModList.cpp b/api/logic/minecraft/ModList.cpp
index 3f28f7d4..02b09eef 100644
--- a/api/logic/minecraft/ModList.cpp
+++ b/api/logic/minecraft/ModList.cpp
@@ -341,7 +341,6 @@ bool ModList::dropMimeData(const QMimeData* data, Qt::DropAction action, int, in
 	if (data->hasUrls())
 	{
 		bool was_watching = is_watching;
-		bool added = false;
 		if (was_watching)
 		{
 			stopWatching();
@@ -355,10 +354,8 @@ bool ModList::dropMimeData(const QMimeData* data, Qt::DropAction action, int, in
 				continue;
 			}
 			// TODO: implement not only copy, but also move
-			if (installMod(url.toLocalFile()))
-			{
-				added = true;
-			}
+			// FIXME: handle errors here
+			installMod(url.toLocalFile());
 		}
 		if (was_watching)
 		{
diff --git a/api/logic/minecraft/ParseUtils_test.cpp b/api/logic/minecraft/ParseUtils_test.cpp
index 79bed1d4..1ce96248 100644
--- a/api/logic/minecraft/ParseUtils_test.cpp
+++ b/api/logic/minecraft/ParseUtils_test.cpp
@@ -22,7 +22,7 @@ slots:
 			"2016-02-10T15:06:41+00:00",
 			"2016-02-04T15:28:02-05:33"
 		};
-		for(int i = 0; i < (sizeof(timestamps) / sizeof(const char *)); i++)
+		for(unsigned i = 0; i < (sizeof(timestamps) / sizeof(const char *)); i++)
 		{
 			QTest::newRow(timestamps[i]) << QString(timestamps[i]);
 		}
diff --git a/api/logic/minecraft/forge/ForgeXzDownload.cpp b/api/logic/minecraft/forge/ForgeXzDownload.cpp
index 4d94dd12..593aa24f 100644
--- a/api/logic/minecraft/forge/ForgeXzDownload.cpp
+++ b/api/logic/minecraft/forge/ForgeXzDownload.cpp
@@ -210,7 +210,8 @@ void ForgeXzDownload::decompressAndInstall()
 
 			if (b.out_pos == sizeof(out))
 			{
-				if (pack200_file.write((char *)out, b.out_pos) != b.out_pos)
+				auto wresult = pack200_file.write((char *)out, b.out_pos);
+				if (wresult < 0 || size_t(wresult) != b.out_pos)
 				{
 					// msg = "Write error\n";
 					xz_dec_end(s);
@@ -230,7 +231,8 @@ void ForgeXzDownload::decompressAndInstall()
 				continue;
 			}
 
-			if (pack200_file.write((char *)out, b.out_pos) != b.out_pos)
+			auto wresult = pack200_file.write((char *)out, b.out_pos);
+			if (wresult < 0 || size_t(wresult) != b.out_pos)
 			{
 				// write error
 				pack200_file.close();
diff --git a/api/logic/minecraft/onesix/OneSixProfileStrategy.cpp b/api/logic/minecraft/onesix/OneSixProfileStrategy.cpp
index 0b83c2e1..ef2a7294 100644
--- a/api/logic/minecraft/onesix/OneSixProfileStrategy.cpp
+++ b/api/logic/minecraft/onesix/OneSixProfileStrategy.cpp
@@ -158,7 +158,6 @@ void OneSixProfileStrategy::loadUserPatches()
 	// now add all the patches by user sort order
 	ProfileUtils::PatchOrder userOrder;
 	ProfileUtils::readOverrideOrders(FS::PathCombine(m_instance->instanceRoot(), "order.json"), userOrder);
-	bool orderIsDirty = false;
 	for (auto uid : userOrder)
 	{
 		// ignore builtins
@@ -169,7 +168,6 @@ void OneSixProfileStrategy::loadUserPatches()
 		// ordering has a patch that is gone?
 		if(!loadedPatches.contains(uid))
 		{
-			orderIsDirty = true;
 			continue;
 		}
 		profile->appendPatch(loadedPatches.take(uid));
diff --git a/api/logic/net/Download.cpp b/api/logic/net/Download.cpp
index ee872e33..12c1b201 100644
--- a/api/logic/net/Download.cpp
+++ b/api/logic/net/Download.cpp
@@ -85,6 +85,7 @@ void Download::start()
 		case Job_InProgress:
 			qDebug() << "Downloading " << m_url.toString();
 			break;
+		case Job_Failed_Proceed: // this is meaningless in this context. We do need a sink.
 		case Job_NotStarted:
 		case Job_Failed:
 			emit failed(m_index_within_job);
diff --git a/api/logic/net/PasteUpload.h b/api/logic/net/PasteUpload.h
index 06e3f955..78d1da8e 100644
--- a/api/logic/net/PasteUpload.h
+++ b/api/logic/net/PasteUpload.h
@@ -20,7 +20,7 @@ public:
 	{
 		return m_pasteID;
 	}
-	uint32_t maxSize()
+	int maxSize()
 	{
 		// 2MB for paste.ee - public
 		if(m_key == "public")
diff --git a/application/MultiMC.h b/application/MultiMC.h
index 2fa8e8c3..c9bba2f8 100644
--- a/application/MultiMC.h
+++ b/application/MultiMC.h
@@ -47,8 +47,6 @@ public:
 	enum Status
 	{
 		StartingUp,
-		UnwritableLog,
-		FailedShowError,
 		Failed,
 		Succeeded,
 		Initialized
diff --git a/application/groupview/GroupView.cpp b/application/groupview/GroupView.cpp
index 75d50483..ec5f409a 100644
--- a/application/groupview/GroupView.cpp
+++ b/application/groupview/GroupView.cpp
@@ -407,7 +407,7 @@ void GroupView::paintEvent(QPaintEvent *event)
 
 	QPainter painter(this->viewport());
 
-	QStyleOptionViewItemV4 option(viewOptions());
+	QStyleOptionViewItem option(viewOptions());
 	option.widget = this;
 
 	int wpWidth = viewport()->width();
@@ -437,8 +437,7 @@ void GroupView::paintEvent(QPaintEvent *event)
 		}
 		Qt::ItemFlags flags = index.flags();
 		option.rect = visualRect(index);
-		option.features |=
-			QStyleOptionViewItemV2::WrapText; // FIXME: what is the meaning of this anyway?
+		option.features |= QStyleOptionViewItem::WrapText;
 		if (flags & Qt::ItemIsSelectable && selectionModel()->isSelected(index))
 		{
 			option.state |= selectionModel()->isSelected(index) ? QStyle::State_Selected
diff --git a/application/groupview/InstanceDelegate.cpp b/application/groupview/InstanceDelegate.cpp
index ffeb256f..10e31178 100644
--- a/application/groupview/InstanceDelegate.cpp
+++ b/application/groupview/InstanceDelegate.cpp
@@ -52,7 +52,7 @@ ListViewDelegate::ListViewDelegate(QObject *parent) : QStyledItemDelegate(parent
 {
 }
 
-void drawSelectionRect(QPainter *painter, const QStyleOptionViewItemV4 &option,
+void drawSelectionRect(QPainter *painter, const QStyleOptionViewItem &option,
 					   const QRect &rect)
 {
 	if ((option.state & QStyle::State_Selected))
@@ -65,7 +65,7 @@ void drawSelectionRect(QPainter *painter, const QStyleOptionViewItemV4 &option,
 	}
 }
 
-void drawFocusRect(QPainter *painter, const QStyleOptionViewItemV4 &option, const QRect &rect)
+void drawFocusRect(QPainter *painter, const QStyleOptionViewItem &option, const QRect &rect)
 {
 	if (!(option.state & QStyle::State_HasFocus))
 		return;
@@ -89,7 +89,7 @@ void drawFocusRect(QPainter *painter, const QStyleOptionViewItemV4 &option, cons
 }
 
 // TODO this can be made a lot prettier
-void drawProgressOverlay(QPainter *painter, const QStyleOptionViewItemV4 &option,
+void drawProgressOverlay(QPainter *painter, const QStyleOptionViewItem &option,
 						 const int value, const int maximum)
 {
 	if (maximum == 0 || value == maximum)
@@ -109,7 +109,7 @@ void drawProgressOverlay(QPainter *painter, const QStyleOptionViewItemV4 &option
 	painter->restore();
 }
 
-void drawBadges(QPainter *painter, const QStyleOptionViewItemV4 &option, BaseInstance *instance, QIcon::Mode mode, QIcon::State state)
+void drawBadges(QPainter *painter, const QStyleOptionViewItem &option, BaseInstance *instance, QIcon::Mode mode, QIcon::State state)
 {
 	QList<QString> pixmaps;
 	if (instance->isRunning())
@@ -156,7 +156,7 @@ void drawBadges(QPainter *painter, const QStyleOptionViewItemV4 &option, BaseIns
 	painter->translate(-option.rect.topLeft());
 }
 
-static QSize viewItemTextSize(const QStyleOptionViewItemV4 *option)
+static QSize viewItemTextSize(const QStyleOptionViewItem *option)
 {
 	QStyle *style = option->widget ? option->widget->style() : QApplication::style();
 	QTextOption textOption;
@@ -177,7 +177,7 @@ static QSize viewItemTextSize(const QStyleOptionViewItemV4 *option)
 void ListViewDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
 							 const QModelIndex &index) const
 {
-	QStyleOptionViewItemV4 opt = option;
+	QStyleOptionViewItem opt = option;
 	initStyleOption(&opt, index);
 	painter->save();
 	painter->setClipRect(opt.rect);
@@ -205,7 +205,7 @@ void ListViewDelegate::paint(QPainter *painter, const QStyleOptionViewItem &opti
 		// FIXME: unused
 		// QSize textSize = viewItemTextSize ( &opt );
 		QPalette::ColorGroup cg;
-		QStyleOptionViewItemV4 opt2(opt);
+		QStyleOptionViewItem opt2(opt);
 
 		if ((opt.widget && opt.widget->isEnabled()) || (opt.state & QStyle::State_Enabled))
 		{
@@ -323,7 +323,7 @@ void ListViewDelegate::paint(QPainter *painter, const QStyleOptionViewItem &opti
 QSize ListViewDelegate::sizeHint(const QStyleOptionViewItem &option,
 								 const QModelIndex &index) const
 {
-	QStyleOptionViewItemV4 opt = option;
+	QStyleOptionViewItem opt = option;
 	initStyleOption(&opt, index);
 	opt.features |= QStyleOptionViewItem::WrapText;
 	opt.text = index.data().toString();