diff --git a/CMakeLists.txt b/CMakeLists.txt
index 72d75a99..c85eb9ba 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -32,7 +32,7 @@ set(CMAKE_C_STANDARD_REQUIRED true)
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_C_STANDARD 11)
 include(GenerateExportHeader)
-set(CMAKE_CXX_FLAGS " -Wall -D_GLIBCXX_USE_CXX11_ABI=0 ${CMAKE_CXX_FLAGS}")
+set(CMAKE_CXX_FLAGS " -Wall -pedantic -Werror -D_GLIBCXX_USE_CXX11_ABI=0 ${CMAKE_CXX_FLAGS}")
 if(UNIX AND APPLE)
 	set(CMAKE_CXX_FLAGS " -stdlib=libc++ ${CMAKE_CXX_FLAGS}")
 endif()
diff --git a/api/gui/DesktopServices.h b/api/gui/DesktopServices.h
index 9daf192a..f64a62c5 100644
--- a/api/gui/DesktopServices.h
+++ b/api/gui/DesktopServices.h
@@ -34,4 +34,4 @@ namespace DesktopServices
 	 * Open the URL, most likely in a browser. Maybe.
 	 */
 	MULTIMC_GUI_EXPORT bool openUrl(const QUrl &url);
-};
+}
diff --git a/api/logic/Version.h b/api/logic/Version.h
index 08dfb6e9..7aa2ebe8 100644
--- a/api/logic/Version.h
+++ b/api/logic/Version.h
@@ -7,8 +7,9 @@
 
 class QUrl;
 
-struct MULTIMC_LOGIC_EXPORT Version
+class MULTIMC_LOGIC_EXPORT Version
 {
+public:
 	Version(const QString &str);
 	Version() {}
 
diff --git a/api/logic/meta/JsonFormat.h b/api/logic/meta/JsonFormat.h
index 762a36f6..cc2c8f83 100644
--- a/api/logic/meta/JsonFormat.h
+++ b/api/logic/meta/JsonFormat.h
@@ -80,4 +80,4 @@ void serializeRequires(QJsonObject & objOut, RequireSet* ptr, const char * keyNa
 MetadataVersion currentFormatVersion();
 }
 
-Q_DECLARE_METATYPE(std::set<Meta::Require>);
\ No newline at end of file
+Q_DECLARE_METATYPE(std::set<Meta::Require>)
diff --git a/api/logic/minecraft/Component.cpp b/api/logic/minecraft/Component.cpp
index c6e41e65..7c52271e 100644
--- a/api/logic/minecraft/Component.cpp
+++ b/api/logic/minecraft/Component.cpp
@@ -145,7 +145,7 @@ QDateTime Component::getReleaseDateTime()
 bool Component::isEnabled()
 {
 	return !canBeDisabled() || !m_disabled;
-};
+}
 
 bool Component::canBeDisabled()
 {
@@ -171,7 +171,7 @@ bool Component::setEnabled(bool state)
 bool Component::isCustom()
 {
 	return m_file != nullptr;
-};
+}
 
 bool Component::isCustomizable()
 {
diff --git a/api/logic/minecraft/Library.cpp b/api/logic/minecraft/Library.cpp
index cd1afde4..237edaf1 100644
--- a/api/logic/minecraft/Library.cpp
+++ b/api/logic/minecraft/Library.cpp
@@ -59,7 +59,7 @@ QList< std::shared_ptr< NetAction > > Library::getDownloads(OpSys system, class
 	bool local = isLocal();
 	bool isForge = (hint() == "forge-pack-xz");
 
-	auto add_download = [&](QString storage, QString url, QString sha1 = QString())
+	auto add_download = [&](QString storage, QString url, QString sha1)
 	{
 		auto entry = cache->resolveEntry("libraries", storage);
 		if(isAlwaysStale)
@@ -208,14 +208,14 @@ QList< std::shared_ptr< NetAction > > Library::getDownloads(OpSys system, class
 		{
 			QString cooked_storage = raw_storage;
 			QString cooked_dl = raw_dl;
-			add_download(cooked_storage.replace("${arch}", "32"), cooked_dl.replace("${arch}", "32"));
+			add_download(cooked_storage.replace("${arch}", "32"), cooked_dl.replace("${arch}", "32"), QString());
 			cooked_storage = raw_storage;
 			cooked_dl = raw_dl;
-			add_download(cooked_storage.replace("${arch}", "64"), cooked_dl.replace("${arch}", "64"));
+			add_download(cooked_storage.replace("${arch}", "64"), cooked_dl.replace("${arch}", "64"), QString());
 		}
 		else
 		{
-			add_download(raw_storage, raw_dl);
+			add_download(raw_storage, raw_dl, QString());
 		}
 	}
 	return out;
diff --git a/api/logic/minecraft/MinecraftInstance.h b/api/logic/minecraft/MinecraftInstance.h
index 446a39d5..3be15b1c 100644
--- a/api/logic/minecraft/MinecraftInstance.h
+++ b/api/logic/minecraft/MinecraftInstance.h
@@ -18,7 +18,7 @@ public:
 	MinecraftInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
 	virtual ~MinecraftInstance() {};
 	virtual void init() override;
-	virtual void saveNow();
+	virtual void saveNow() override;
 
 	// FIXME: remove
 	QString typeName() const override;
diff --git a/api/logic/minecraft/World.cpp b/api/logic/minecraft/World.cpp
index 227a9b75..d7bc4553 100644
--- a/api/logic/minecraft/World.cpp
+++ b/api/logic/minecraft/World.cpp
@@ -275,7 +275,7 @@ static QString read_string (nbt::value& parent, const char * name, const QString
 		qWarning() << "NBT tag" << name << "could not be converted to string. Defaulting to" << fallback;
 		return fallback;
 	}
-};
+}
 
 static int64_t read_long (nbt::value& parent, const char * name, const int64_t & fallback = 0)
 {
@@ -301,7 +301,7 @@ static int64_t read_long (nbt::value& parent, const char * name, const int64_t &
 		qWarning() << "NBT tag" << name << "could not be converted to long. Defaulting to" << fallback;
 		return fallback;
 	}
-};
+}
 
 void World::loadFromLevelDat(QByteArray data)
 {
diff --git a/api/logic/minecraft/launch/ModMinecraftJar.h b/api/logic/minecraft/launch/ModMinecraftJar.h
index b9a2d35b..dca484f8 100644
--- a/api/logic/minecraft/launch/ModMinecraftJar.h
+++ b/api/logic/minecraft/launch/ModMinecraftJar.h
@@ -25,8 +25,8 @@ public:
 	explicit ModMinecraftJar(LaunchTask *parent) : LaunchStep(parent) {};
 	virtual ~ModMinecraftJar(){};
 
-	virtual void executeTask();
-	virtual bool canAbort() const
+	virtual void executeTask() override;
+	virtual bool canAbort() const override
 	{
 		return false;
 	}
diff --git a/api/logic/modplatform/ftb/FtbPackInstallTask.cpp b/api/logic/modplatform/ftb/FtbPackInstallTask.cpp
index b57c2092..7815ef46 100644
--- a/api/logic/modplatform/ftb/FtbPackInstallTask.cpp
+++ b/api/logic/modplatform/ftb/FtbPackInstallTask.cpp
@@ -57,7 +57,7 @@ void FtbPackInstallTask::onDownloadProgress(qint64 current, qint64 total)
 {
 	abortable = true;
 	progress(current, total * 4);
-	setStatus(tr("Downloading zip for %1 (%2\%)").arg(m_pack.name).arg(current / 10));
+	setStatus(tr("Downloading zip for %1 (%2%)").arg(m_pack.name).arg(current / 10));
 }
 
 void FtbPackInstallTask::unzip()
diff --git a/api/logic/net/FileSink.cpp b/api/logic/net/FileSink.cpp
index f52c5788..e3ff0498 100644
--- a/api/logic/net/FileSink.cpp
+++ b/api/logic/net/FileSink.cpp
@@ -10,12 +10,12 @@ FileSink::FileSink(QString filename)
 	:m_filename(filename)
 {
 	// nil
-};
+}
 
 FileSink::~FileSink()
 {
 	// nil
-};
+}
 
 JobStatus FileSink::init(QNetworkRequest& request)
 {
diff --git a/api/logic/net/MetaCacheSink.cpp b/api/logic/net/MetaCacheSink.cpp
index c9d75310..b4b337d6 100644
--- a/api/logic/net/MetaCacheSink.cpp
+++ b/api/logic/net/MetaCacheSink.cpp
@@ -10,12 +10,12 @@ MetaCacheSink::MetaCacheSink(MetaEntryPtr entry, ChecksumValidator * md5sum)
 	:Net::FileSink(entry->getFullPath()), m_entry(entry), m_md5Node(md5sum)
 {
 	addValidator(md5sum);
-};
+}
 
 MetaCacheSink::~MetaCacheSink()
 {
 	// nil
-};
+}
 
 JobStatus MetaCacheSink::initCache(QNetworkRequest& request)
 {
diff --git a/api/logic/updater/GoUpdate.h b/api/logic/updater/GoUpdate.h
index 95f26b8c..0e183b9f 100644
--- a/api/logic/updater/GoUpdate.h
+++ b/api/logic/updater/GoUpdate.h
@@ -133,4 +133,4 @@ bool MULTIMC_LOGIC_EXPORT processFileLists
 bool MULTIMC_LOGIC_EXPORT fixPathForOSX(QString &path);
 
 }
-Q_DECLARE_METATYPE(GoUpdate::Status);
\ No newline at end of file
+Q_DECLARE_METATYPE(GoUpdate::Status)
diff --git a/application/VersionProxyModel.cpp b/application/VersionProxyModel.cpp
index d59fceee..990b949e 100644
--- a/application/VersionProxyModel.cpp
+++ b/application/VersionProxyModel.cpp
@@ -227,7 +227,7 @@ QVariant VersionProxyModel::data(const QModelIndex &index, int role) const
 			return QVariant();
 		}
 	}
-};
+}
 
 QModelIndex VersionProxyModel::parent(const QModelIndex &child) const
 {
diff --git a/application/pages/BasePageProvider.h b/application/pages/BasePageProvider.h
index 1cc7458a..05c38d23 100644
--- a/application/pages/BasePageProvider.h
+++ b/application/pages/BasePageProvider.h
@@ -34,6 +34,7 @@ public:
 		: m_dialogTitle(dialogTitle)
 	{
 	}
+	virtual ~GenericPageProvider() {}
 
 	QList<BasePage *> getPages() override
 	{
diff --git a/application/setupwizard/AnalyticsWizardPage.h b/application/setupwizard/AnalyticsWizardPage.h
index 03de9cb0..0234f02a 100644
--- a/application/setupwizard/AnalyticsWizardPage.h
+++ b/application/setupwizard/AnalyticsWizardPage.h
@@ -8,7 +8,7 @@ class QCheckBox;
 
 class AnalyticsWizardPage : public BaseWizardPage
 {
-	Q_OBJECT;
+	Q_OBJECT
 public:
 	explicit AnalyticsWizardPage(QWidget *parent = Q_NULLPTR);
 	virtual ~AnalyticsWizardPage();
diff --git a/application/setupwizard/JavaWizardPage.h b/application/setupwizard/JavaWizardPage.h
index 4ea31d24..592fa24c 100644
--- a/application/setupwizard/JavaWizardPage.h
+++ b/application/setupwizard/JavaWizardPage.h
@@ -6,7 +6,7 @@ class JavaSettingsWidget;
 
 class JavaWizardPage : public BaseWizardPage
 {
-	Q_OBJECT;
+	Q_OBJECT
 public:
 	explicit JavaWizardPage(QWidget *parent = Q_NULLPTR);
 
diff --git a/application/setupwizard/LanguageWizardPage.h b/application/setupwizard/LanguageWizardPage.h
index 8b55d57f..5a9e882d 100644
--- a/application/setupwizard/LanguageWizardPage.h
+++ b/application/setupwizard/LanguageWizardPage.h
@@ -7,7 +7,7 @@ class QListView;
 
 class LanguageWizardPage : public BaseWizardPage
 {
-	Q_OBJECT;
+	Q_OBJECT
 public:
 	explicit LanguageWizardPage(QWidget *parent = Q_NULLPTR);
 
diff --git a/libraries/classparser/src/constants.h b/libraries/classparser/src/constants.h
index 9c74ab20..c3ef88fd 100644
--- a/libraries/classparser/src/constants.h
+++ b/libraries/classparser/src/constants.h
@@ -123,7 +123,26 @@ public:
 		return ss.str();
 	}
 
+	struct ref_type_t
+	{
+		/**
+		 * Class reference:
+		 * an index within the constant pool to a UTF-8 string containing
+		 * the fully qualified class name (in internal format)
+		 * Used for j_class, j_fieldref, j_methodref and j_interface_methodref
+		 */
+		uint16_t class_idx;
+		// used for j_fieldref, j_methodref and j_interface_methodref
+		uint16_t name_and_type_idx;
+	};
+	struct name_and_type_t
+	{
+		uint16_t name_index;
+		uint16_t descriptor_index;
+	};
+
 	std::string str_data; /** String data in 'modified utf-8'.*/
+
 	// store everything here.
 	union
 	{
@@ -132,23 +151,8 @@ public:
 		float float_data;
 		double double_data;
 		uint16_t index;
-		struct
-		{
-			/**
-			 * Class reference:
-			 *   an index within the constant pool to a UTF-8 string containing
-			 *   the fully qualified class name (in internal format)
-			 * Used for j_class, j_fieldref, j_methodref and j_interface_methodref
-			 */
-			uint16_t class_idx;
-			// used for j_fieldref, j_methodref and j_interface_methodref
-			uint16_t name_and_type_idx;
-		} ref_type;
-		struct
-		{
-			uint16_t name_index;
-			uint16_t descriptor_index;
-		} name_and_type;
+		ref_type_t ref_type;
+		name_and_type_t name_and_type;
 	};
 };
 
diff --git a/libraries/classparser/src/javaendian.h b/libraries/classparser/src/javaendian.h
index d488b382..5e6fff55 100644
--- a/libraries/classparser/src/javaendian.h
+++ b/libraries/classparser/src/javaendian.h
@@ -44,33 +44,33 @@ inline uint64_t bigswap(uint64_t x)
 		   ((x << 8) & 0x000000FF00000000) | ((x >> 8) & 0x00000000FF000000) |
 		   ((x >> 24) & 0x0000000000FF0000) | ((x >> 40) & 0x000000000000FF00) | (x << 56);
 }
-;
+
 inline uint32_t bigswap(uint32_t x)
 {
 	return (x >> 24) | ((x << 8) & 0x00FF0000) | ((x >> 8) & 0x0000FF00) | (x << 24);
 }
-;
+
 inline uint16_t bigswap(uint16_t x)
 {
 	return (x >> 8) | (x << 8);
 }
-;
+
 inline int64_t bigswap(int64_t x)
 {
 	return (x >> 56) | ((x << 40) & 0x00FF000000000000) | ((x << 24) & 0x0000FF0000000000) |
 		   ((x << 8) & 0x000000FF00000000) | ((x >> 8) & 0x00000000FF000000) |
 		   ((x >> 24) & 0x0000000000FF0000) | ((x >> 40) & 0x000000000000FF00) | (x << 56);
 }
-;
+
 inline int32_t bigswap(int32_t x)
 {
 	return (x >> 24) | ((x << 8) & 0x00FF0000) | ((x >> 8) & 0x0000FF00) | (x << 24);
 }
-;
+
 inline int16_t bigswap(int16_t x)
 {
 	return (x >> 8) | (x << 8);
 }
-;
+
 #endif
 }
diff --git a/libraries/iconfix/xdgicon.cpp b/libraries/iconfix/xdgicon.cpp
index a36d80a9..84665a7d 100644
--- a/libraries/iconfix/xdgicon.cpp
+++ b/libraries/iconfix/xdgicon.cpp
@@ -52,7 +52,7 @@ struct QtIconCache : public IconCache
 	}
 };
 }
-Q_GLOBAL_STATIC(IconCache, qtIconCache);
+Q_GLOBAL_STATIC(IconCache, qtIconCache)
 
 static void qt_cleanup_icon_cache()
 {