diff --git a/aegisub/src/aegisublocale.cpp b/aegisub/src/aegisublocale.cpp
index 2910d96ce..90d162a76 100644
--- a/aegisub/src/aegisublocale.cpp
+++ b/aegisub/src/aegisublocale.cpp
@@ -107,7 +107,7 @@ wxString AegisubLocale::PickLanguage() {
 	if (!active_language.empty())
 		style |= wxCANCEL;
 
-	wxSingleChoiceDialog dialog(NULL, "Please choose a language:", "Language", langNames,
+	wxSingleChoiceDialog dialog(nullptr, "Please choose a language:", "Language", langNames,
 #if wxCHECK_VERSION(2, 9, 4)
 			(void **)0,
 #else
diff --git a/aegisub/src/ass_dialogue.h b/aegisub/src/ass_dialogue.h
index b5e8c7866..892c7ce4b 100644
--- a/aegisub/src/ass_dialogue.h
+++ b/aegisub/src/ass_dialogue.h
@@ -162,7 +162,7 @@ public:
 	/// @brief Process parameters via callback
 	/// @param callback The callback function to call per tag parameter
 	/// @param userData User data to pass to callback function
-	void ProcessParameters(AssDialogueBlockOverride::ProcessParametersCallback callback,void *userData=NULL);
+	void ProcessParameters(AssDialogueBlockOverride::ProcessParametersCallback callback,void *userData=nullptr);
 	/// Strip all ASS tags from the text
 	void StripTags();
 	/// Strip a specific ASS tag from the text
diff --git a/aegisub/src/ass_export_filter.h b/aegisub/src/ass_export_filter.h
index 32f1df6c0..658df6937 100644
--- a/aegisub/src/ass_export_filter.h
+++ b/aegisub/src/ass_export_filter.h
@@ -64,7 +64,7 @@ public:
 	static void Unregister(AssExportFilter *filter);
 	/// Unregister and delete all export filters
 	static void Clear();
-	/// Get a filter by name or NULL if it doesn't exist
+	/// Get a filter by name or nullptr if it doesn't exist
 	static AssExportFilter *GetFilter(wxString const& name);
 
 	/// Get the list of registered filters
diff --git a/aegisub/src/ass_file.h b/aegisub/src/ass_file.h
index 8d15d41da..a7e4f800d 100644
--- a/aegisub/src/ass_file.h
+++ b/aegisub/src/ass_file.h
@@ -114,7 +114,7 @@ public:
 	wxArrayString GetStyles() const;
 	/// @brief Get a style by name
 	/// @param name Style name
-	/// @return Pointer to style or NULL
+	/// @return Pointer to style or nullptr
 	AssStyle *GetStyle(wxString const& name);
 
 	void swap(AssFile &) throw();
diff --git a/aegisub/src/ass_style_storage.h b/aegisub/src/ass_style_storage.h
index a494dd1ee..bfddea3af 100644
--- a/aegisub/src/ass_style_storage.h
+++ b/aegisub/src/ass_style_storage.h
@@ -74,7 +74,7 @@ public:
 
 	/// Get the style with the given name
 	/// @param name Case-insensitive style name
-	/// @return Style or NULL if the requested style is not found
+	/// @return Style or nullptr if the requested style is not found
 	AssStyle *GetStyle(wxString const& name);
 
 	/// Save stored styles to a file
diff --git a/aegisub/src/audio_player.cpp b/aegisub/src/audio_player.cpp
index a4af83d63..8e2b90eaa 100644
--- a/aegisub/src/audio_player.cpp
+++ b/aegisub/src/audio_player.cpp
@@ -90,4 +90,4 @@ void AudioPlayerFactory::RegisterProviders() {
 #endif
 }
 
-template<> AudioPlayerFactory::map *FactoryBase<AudioPlayer *(*)(AudioProvider*)>::classes = NULL;
+template<> AudioPlayerFactory::map *FactoryBase<AudioPlayer *(*)(AudioProvider*)>::classes = nullptr;
diff --git a/aegisub/src/audio_player_dsound.cpp b/aegisub/src/audio_player_dsound.cpp
index 454b1f8cd..5eefaedc3 100644
--- a/aegisub/src/audio_player_dsound.cpp
+++ b/aegisub/src/audio_player_dsound.cpp
@@ -60,7 +60,7 @@ DirectSoundPlayer::DirectSoundPlayer(AudioProvider *provider)
 {
 	// Initialize the DirectSound object
 	HRESULT res;
-	res = DirectSoundCreate8(&DSDEVID_DefaultPlayback,&directSound,NULL); // TODO: support selecting audio device
+	res = DirectSoundCreate8(&DSDEVID_DefaultPlayback,&directSound,nullptr); // TODO: support selecting audio device
 	if (FAILED(res)) throw agi::AudioPlayerOpenError("Failed initializing DirectSound", 0);
 
 	// Set DirectSound parameters
@@ -91,7 +91,7 @@ DirectSoundPlayer::DirectSoundPlayer(AudioProvider *provider)
 
 	// Create the buffer
 	IDirectSoundBuffer *buf;
-	res = directSound->CreateSoundBuffer(&desc,&buf,NULL);
+	res = directSound->CreateSoundBuffer(&desc,&buf,nullptr);
 	if (res != DS_OK) throw agi::AudioPlayerOpenError("Failed creating DirectSound buffer", 0);
 
 	// Copy interface to buffer
@@ -108,13 +108,13 @@ DirectSoundPlayer::~DirectSoundPlayer() {
 	// Unref the DirectSound buffer
 	if (buffer) {
 		buffer->Release();
-		buffer = NULL;
+		buffer = nullptr;
 	}
 
 	// Unref the DirectSound object
 	if (directSound) {
 		directSound->Release();
-		directSound = NULL;
+		directSound = nullptr;
 	}
 }
 
@@ -138,7 +138,7 @@ bool DirectSoundPlayer::FillBuffer(bool fill) {
 	}
 	else {
 		DWORD bufplay;
-		res = buffer->GetCurrentPosition(&bufplay, NULL);
+		res = buffer->GetCurrentPosition(&bufplay, nullptr);
 		if (FAILED(res)) return false;
 		toWrite = (int)bufplay - (int)offset;
 		if (toWrite < 0) toWrite += bufSize;
@@ -255,7 +255,7 @@ void DirectSoundPlayer::Stop() {
 			thread->Stop();
 			thread->Wait();
 		}
-		thread = NULL;
+		thread = nullptr;
 	}
 	// The thread is now guaranteed dead and there are no concurrency problems to worry about
 
@@ -304,7 +304,7 @@ int64_t DirectSoundPlayer::GetCurrentPosition() {
 ///
 DirectSoundPlayerThread::DirectSoundPlayerThread(DirectSoundPlayer *par) : wxThread(wxTHREAD_JOINABLE) {
 	parent = par;
-	stopnotify = CreateEvent(NULL, true, false, NULL);
+	stopnotify = CreateEvent(nullptr, true, false, nullptr);
 }
 
 /// @brief Thread destructor
@@ -336,7 +336,7 @@ wxThread::ExitCode DirectSoundPlayerThread::Entry() {
 		DWORD size1, size2;
 		DWORD playpos;
 		HRESULT res;
-		res = parent->buffer->GetCurrentPosition(&playpos, NULL);
+		res = parent->buffer->GetCurrentPosition(&playpos, nullptr);
 		if (FAILED(res)) break;
 		int toWrite = playpos - parent->offset;
 		while (toWrite < 0) toWrite += parent->bufSize;
diff --git a/aegisub/src/audio_player_dsound2.cpp b/aegisub/src/audio_player_dsound2.cpp
index 9a7b292e5..136c70dd9 100644
--- a/aegisub/src/audio_player_dsound2.cpp
+++ b/aegisub/src/audio_player_dsound2.cpp
@@ -75,7 +75,7 @@ struct COMInitialization {
 	{
 		if (!inited)
 		{
-			if (FAILED(CoInitialize(NULL)))
+			if (FAILED(CoInitialize(nullptr)))
 				throw std::exception();
 			inited = true;
 		}
@@ -290,7 +290,7 @@ void DirectSoundPlayer2Thread::Run()
 
 	// Create DirectSound object
 	COMObjectRetainer<IDirectSound8> ds;
-	if (FAILED(DirectSoundCreate8(&DSDEVID_DefaultPlayback, &ds.obj, NULL)))
+	if (FAILED(DirectSoundCreate8(&DSDEVID_DefaultPlayback, &ds.obj, nullptr)))
 		REPORT_ERROR("Cound not create DirectSound object")
 
 
diff --git a/aegisub/src/audio_player_oss.cpp b/aegisub/src/audio_player_oss.cpp
index a314d4f09..4f85ad9cf 100644
--- a/aegisub/src/audio_player_oss.cpp
+++ b/aegisub/src/audio_player_oss.cpp
@@ -146,7 +146,7 @@ void OSSPlayer::Stop()
     }
 
     // errors can be ignored here
-    ioctl(dspdev, SNDCTL_DSP_RESET, NULL);
+    ioctl(dspdev, SNDCTL_DSP_RESET, nullptr);
 
     // Reset data
     playing = false;
@@ -160,7 +160,7 @@ void OSSPlayer::SetEndPosition(int64_t pos)
     end_frame = pos;
 
     if (pos <= GetCurrentPosition()) {
-        ioctl(dspdev, SNDCTL_DSP_RESET, NULL);
+        ioctl(dspdev, SNDCTL_DSP_RESET, nullptr);
         if (thread && thread->IsAlive())
             thread->Delete();
     }
diff --git a/aegisub/src/audio_player_portaudio.cpp b/aegisub/src/audio_player_portaudio.cpp
index edd1c6717..c692cf3e3 100644
--- a/aegisub/src/audio_player_portaudio.cpp
+++ b/aegisub/src/audio_player_portaudio.cpp
@@ -153,7 +153,7 @@ void PortAudioPlayer::OpenStream() {
 		pa_output_p.channelCount = provider->GetChannels();
 		pa_output_p.sampleFormat = paInt16;
 		pa_output_p.suggestedLatency = device_info->defaultLowOutputLatency;
-		pa_output_p.hostApiSpecificStreamInfo = NULL;
+		pa_output_p.hostApiSpecificStreamInfo = nullptr;
 
 		LOG_D("audio/player/portaudio") << "OpenStream:"
 			<< " output channels: " << pa_output_p.channelCount
@@ -161,7 +161,7 @@ void PortAudioPlayer::OpenStream() {
 			<< " sample rate: " << provider->GetSampleRate()
 			<< " sample format: " << pa_output_p.sampleFormat;
 
-		PaError err = Pa_OpenStream(&stream, NULL, &pa_output_p, provider->GetSampleRate(), 0, paPrimeOutputBuffersUsingStreamCallback, paCallback, this);
+		PaError err = Pa_OpenStream(&stream, nullptr, &pa_output_p, provider->GetSampleRate(), 0, paPrimeOutputBuffersUsingStreamCallback, paCallback, this);
 
 		if (err == paNoError) {
 			LOG_D("audo/player/portaudio") << "Using device " << pa_output_p.device << " " << device_info->name << " " << Pa_GetHostApiInfo(device_info->hostApi)->name;
diff --git a/aegisub/src/audio_player_pulse.cpp b/aegisub/src/audio_player_pulse.cpp
index 9b8494bbb..5b8f97eba 100644
--- a/aegisub/src/audio_player_pulse.cpp
+++ b/aegisub/src/audio_player_pulse.cpp
@@ -80,7 +80,7 @@ PulseAudioPlayer::PulseAudioPlayer(AudioProvider *provider)
 	pa_context_set_state_callback(context, (pa_context_notify_cb_t)pa_context_notify, this);
 
 	// Connect the context
-	pa_context_connect(context, NULL, PA_CONTEXT_NOAUTOSPAWN, NULL);
+	pa_context_connect(context, nullptr, PA_CONTEXT_NOAUTOSPAWN, nullptr);
 
 	// Wait for connection
 	while (true) {
@@ -120,7 +120,7 @@ PulseAudioPlayer::PulseAudioPlayer(AudioProvider *provider)
 	pa_stream_set_write_callback(stream, (pa_stream_request_cb_t)pa_stream_write, this);
 
 	// Connect stream
-	paerror = pa_stream_connect_playback(stream, NULL, NULL, (pa_stream_flags_t)(PA_STREAM_INTERPOLATE_TIMING|PA_STREAM_NOT_MONOTONOUS|PA_STREAM_AUTO_TIMING_UPDATE), NULL, NULL);
+	paerror = pa_stream_connect_playback(stream, nullptr, nullptr, (pa_stream_flags_t)(PA_STREAM_INTERPOLATE_TIMING|PA_STREAM_NOT_MONOTONOUS|PA_STREAM_AUTO_TIMING_UPDATE), nullptr, nullptr);
 	if (paerror) {
 		LOG_E("audio/player/pulse") << "Stream connection failed: " << pa_strerror(paerror) << "(" << paerror << ")";
 		throw agi::AudioPlayerOpenError(std::string("PulseAudio reported error: ") + pa_strerror(paerror), 0);
@@ -269,7 +269,7 @@ void PulseAudioPlayer::pa_stream_write(pa_stream *p, size_t length, PulseAudioPl
 	if (thread->cur_frame >= thread->end_frame + thread->provider->GetSampleRate()) {
 		// More than a second past end of stream
 		thread->is_playing = false;
-		pa_operation *op = pa_stream_drain(p, NULL, NULL);
+		pa_operation *op = pa_stream_drain(p, nullptr, nullptr);
 		pa_operation_unref(op);
 		return;
 
diff --git a/aegisub/src/audio_provider.cpp b/aegisub/src/audio_provider.cpp
index e5b8eb6fe..820cfd89d 100644
--- a/aegisub/src/audio_provider.cpp
+++ b/aegisub/src/audio_provider.cpp
@@ -221,4 +221,4 @@ void AudioProviderFactory::RegisterProviders() {
 #endif
 }
 
-template<> AudioProviderFactory::map *FactoryBase<AudioProvider *(*)(wxString)>::classes = NULL;
+template<> AudioProviderFactory::map *FactoryBase<AudioProvider *(*)(wxString)>::classes = nullptr;
diff --git a/aegisub/src/audio_provider_ffmpegsource.cpp b/aegisub/src/audio_provider_ffmpegsource.cpp
index bbf9ae92b..53a63b13b 100644
--- a/aegisub/src/audio_provider_ffmpegsource.cpp
+++ b/aegisub/src/audio_provider_ffmpegsource.cpp
@@ -53,7 +53,7 @@
 /// @brief Constructor
 /// @param filename The filename to open
 FFmpegSourceAudioProvider::FFmpegSourceAudioProvider(wxString filename) try
-: AudioSource(NULL, FFMS_DestroyAudioSource)
+: AudioSource(nullptr, FFMS_DestroyAudioSource)
 {
 	ErrInfo.Buffer		= FFMSErrMsg;
 	ErrInfo.BufferSize	= sizeof(FFMSErrMsg);
@@ -99,7 +99,7 @@ void FFmpegSourceAudioProvider::LoadAudio(wxString filename) {
 		Index(FFMS_ReadIndex(CacheName.utf8_str(), &ErrInfo), FFMS_DestroyIndex);
 
 	if (Index && FFMS_IndexBelongsToFile(Index, FileNameShort.utf8_str(), &ErrInfo))
-		Index = NULL;
+		Index = nullptr;
 
 	// index valid but track number still not set?
 	if (Index) {
@@ -113,7 +113,7 @@ void FFmpegSourceAudioProvider::LoadAudio(wxString filename) {
 		// but do we have indexing info for the desired audio track?
 		FFMS_Track *TempTrackData = FFMS_GetTrackFromIndex(Index, TrackNumber);
 		if (FFMS_GetNumFrames(TempTrackData) <= 0)
-			Index = NULL;
+			Index = nullptr;
 	}
 	// no valid index exists and the file only has one audio track, index it
 	else if (TrackNumber < 0)
@@ -124,7 +124,7 @@ void FFmpegSourceAudioProvider::LoadAudio(wxString filename) {
 	FFMS_IndexErrorHandling ErrorHandling = GetErrorHandlingMode();
 #if FFMS_VERSION >= ((2 << 24) | (17 << 16) | (2 << 8) | 0)
 	if (Index && FFMS_GetErrorHandling(Index) != ErrorHandling)
-		Index = NULL;
+		Index = nullptr;
 #endif
 
 	// moment of truth
diff --git a/aegisub/src/auto4_base.h b/aegisub/src/auto4_base.h
index 292348c89..37d3221d3 100644
--- a/aegisub/src/auto4_base.h
+++ b/aegisub/src/auto4_base.h
@@ -257,7 +257,7 @@ namespace Automation4 {
 		wxString engine_name;
 		wxString filename_pattern;
 
-		/// Load a file, or return NULL if the file is not in a supported
+		/// Load a file, or return nullptr if the file is not in a supported
 		/// format. If the file is in a supported format but is invalid, a
 		/// script should be returned which returns false from IsLoaded and
 		/// an appropriate error message from GetDescription.
diff --git a/aegisub/src/avisynth_wrap.cpp b/aegisub/src/avisynth_wrap.cpp
index f4b8a3092..7472b43eb 100644
--- a/aegisub/src/avisynth_wrap.cpp
+++ b/aegisub/src/avisynth_wrap.cpp
@@ -43,8 +43,8 @@
 // Allocate storage for and initialise static members
 namespace {
 	int avs_refcount = 0;
-	HINSTANCE hLib = NULL;
-	IScriptEnvironment *env = NULL;
+	HINSTANCE hLib = nullptr;
+	IScriptEnvironment *env = nullptr;
 	wxMutex AviSynthMutex;
 }
 
diff --git a/aegisub/src/base_grid.cpp b/aegisub/src/base_grid.cpp
index b8b320864..969871f10 100644
--- a/aegisub/src/base_grid.cpp
+++ b/aegisub/src/base_grid.cpp
@@ -97,7 +97,7 @@ BaseGrid::BaseGrid(wxWindow* parent, agi::Context *context, const wxSize& size,
 , active_line(0)
 , batch_level(0)
 , batch_active_line_changed(false)
-, seek_listener(context->videoController->AddSeekListener(std::bind(&BaseGrid::Refresh, this, false, (wxRect*)NULL)))
+, seek_listener(context->videoController->AddSeekListener(std::bind(&BaseGrid::Refresh, this, false, nullptr)))
 , context_menu(0)
 , yPos(0)
 , context(context)
@@ -134,7 +134,7 @@ BaseGrid::BaseGrid(wxWindow* parent, agi::Context *context, const wxSize& size,
 	OPT_SUB("Colour/Subtitle Grid/Lines", &BaseGrid::UpdateStyle, this);
 	OPT_SUB("Colour/Subtitle Grid/Selection", &BaseGrid::UpdateStyle, this);
 	OPT_SUB("Colour/Subtitle Grid/Standard", &BaseGrid::UpdateStyle, this);
-	OPT_SUB("Subtitle/Grid/Hide Overrides", std::bind(&BaseGrid::Refresh, this, false, (wxRect*)NULL));
+	OPT_SUB("Subtitle/Grid/Hide Overrides", std::bind(&BaseGrid::Refresh, this, false, nullptr));
 
 	Bind(wxEVT_CONTEXT_MENU, &BaseGrid::OnContextMenu, this);
 }
@@ -229,7 +229,7 @@ void BaseGrid::UpdateStyle() {
 		wxClientDC dc(this);
 		dc.SetFont(font);
 		int fw,fh;
-		dc.GetTextExtent("#TWFfgGhH", &fw, &fh, NULL, NULL, &font);
+		dc.GetTextExtent("#TWFfgGhH", &fw, &fh, nullptr, nullptr, &font);
 		lineHeight = fh + 4;
 	}
 
diff --git a/aegisub/src/charset_conv.h b/aegisub/src/charset_conv.h
index d31229130..879c823b1 100644
--- a/aegisub/src/charset_conv.h
+++ b/aegisub/src/charset_conv.h
@@ -48,7 +48,7 @@ public:
 	// wxMBConv implementation; see strconv.h for usage details
 	size_t ToWChar(wchar_t *dst, size_t dstLen, const char *src, size_t srcLen = wxNO_LEN) const;
 	size_t FromWChar(char *dst, size_t dstLen, const wchar_t *src, size_t srcLen = wxNO_LEN) const;
-	wxMBConv *Clone() const { return NULL; };
+	wxMBConv *Clone() const { return nullptr; };
 
 protected:
 	AegisubCSConv();
diff --git a/aegisub/src/dialog_manager.h b/aegisub/src/dialog_manager.h
index 613ada741..f5d28c2eb 100644
--- a/aegisub/src/dialog_manager.h
+++ b/aegisub/src/dialog_manager.h
@@ -98,7 +98,7 @@ public:
 
 	/// Get the dialog of the given type
 	/// @tparam DialogType Type of dialog to get
-	/// @return A pointer to a DialogType or NULL if no dialog of the given type has been created
+	/// @return A pointer to a DialogType or nullptr if no dialog of the given type has been created
 	template<class DialogType>
 	DialogType *Get() const {
 		DialogMap::const_iterator it = created_dialogs.find(&typeid(DialogType));
diff --git a/aegisub/src/dialog_search_replace.cpp b/aegisub/src/dialog_search_replace.cpp
index 52b5482b3..ee21e3dd9 100644
--- a/aegisub/src/dialog_search_replace.cpp
+++ b/aegisub/src/dialog_search_replace.cpp
@@ -265,7 +265,7 @@ void SearchReplaceEngine::ReplaceNext(bool DoReplace) {
 	int start = curLine;
 	int nrows = context->subsGrid->GetRows();
 	bool found = false;
-	wxString *Text = NULL;
+	wxString *Text = nullptr;
 	size_t tempPos;
 	int regFlags = wxRE_ADVANCED;
 	if (!matchCase) {
@@ -452,7 +452,7 @@ void SearchReplaceEngine::OnDialogOpen() {
 }
 
 void SearchReplaceEngine::OpenDialog (bool replace) {
-	static DialogSearchReplace *diag = NULL;
+	static DialogSearchReplace *diag = nullptr;
 
 	// already opened
 	if (diag) {
diff --git a/aegisub/src/dialog_shift_times.cpp b/aegisub/src/dialog_shift_times.cpp
index e5f0bb236..169c0090b 100644
--- a/aegisub/src/dialog_shift_times.cpp
+++ b/aegisub/src/dialog_shift_times.cpp
@@ -135,7 +135,7 @@ DialogShiftTimes::DialogShiftTimes(agi::Context *context)
 	wxString time_field_vals[] = { _("Start a&nd End times"), _("&Start times only"), _("&End times only") };
 	time_fields = new wxRadioBox(this, -1, _("Times"), wxDefaultPosition, wxDefaultSize, 3, time_field_vals, 1);
 
-	history_box = new wxListBox(this, -1, wxDefaultPosition, wxSize(350, 100), 0, NULL, wxLB_HSCROLL);
+	history_box = new wxListBox(this, -1, wxDefaultPosition, wxSize(350, 100), 0, nullptr, wxLB_HSCROLL);
 
 	wxButton *clear_button = new wxButton(this, -1, _("&Clear"));
 	clear_button->Bind(wxEVT_COMMAND_BUTTON_CLICKED, &DialogShiftTimes::OnClear, this);
diff --git a/aegisub/src/dialog_style_editor.cpp b/aegisub/src/dialog_style_editor.cpp
index 8f41c95da..7ed155a86 100644
--- a/aegisub/src/dialog_style_editor.cpp
+++ b/aegisub/src/dialog_style_editor.cpp
@@ -324,8 +324,8 @@ DialogStyleEditor::DialogStyleEditor(wxWindow *parent, AssStyle *style, agi::Con
 	MiscBox->Add(MiscBoxBottom, wxSizerFlags().Expand().Center().Border(wxTOP));
 
 	// Preview
-	SubsPreview = NULL;
-	PreviewText = NULL;
+	SubsPreview = nullptr;
+	PreviewText = nullptr;
 	ColourButton *previewButton = 0;
 	if (!SubtitlesProviderFactory::GetClasses().empty()) {
 		PreviewText = new wxTextCtrl(this, -1, lagi_wxString(OPT_GET("Tool/Style Editor/Preview Text")->GetString()));
diff --git a/aegisub/src/dialog_style_manager.cpp b/aegisub/src/dialog_style_manager.cpp
index 914c09c2b..7b042bec7 100644
--- a/aegisub/src/dialog_style_manager.cpp
+++ b/aegisub/src/dialog_style_manager.cpp
@@ -163,7 +163,7 @@ DialogStyleManager::DialogStyleManager(agi::Context *context)
 
 	// Catalog
 	wxSizer *CatalogBox = new wxStaticBoxSizer(wxHORIZONTAL,this,_("Catalog of available storages"));
-	CatalogList = new wxComboBox(this,-1, "", wxDefaultPosition, wxSize(-1,-1), 0, NULL, wxCB_READONLY);
+	CatalogList = new wxComboBox(this,-1, "", wxDefaultPosition, wxSize(-1,-1), 0, nullptr, wxCB_READONLY);
 	wxButton *CatalogNew = new wxButton(this, -1, _("New"));
 	CatalogDelete = new wxButton(this, -1, _("Delete"));
 	CatalogBox->Add(CatalogList,1,wxEXPAND | wxRIGHT | wxALIGN_RIGHT,5);
@@ -174,7 +174,7 @@ DialogStyleManager::DialogStyleManager(agi::Context *context)
 	wxSizer *StorageButtons = make_edit_buttons(this, _("Copy to &current script ->"), &MoveToLocal, &StorageNew, &StorageEdit, &StorageCopy, &StorageDelete);
 
 	wxSizer *StorageListSizer = new wxBoxSizer(wxHORIZONTAL);
-	StorageList = new wxListBox(this, -1, wxDefaultPosition, wxSize(240,250), 0, NULL, wxLB_EXTENDED);
+	StorageList = new wxListBox(this, -1, wxDefaultPosition, wxSize(240,250), 0, nullptr, wxLB_EXTENDED);
 	StorageListSizer->Add(StorageList,1,wxEXPAND | wxRIGHT,0);
 	StorageListSizer->Add(make_move_buttons(this, &StorageMoveUp, &StorageMoveDown, &StorageMoveTop, &StorageMoveBottom, &StorageSort), wxSizerFlags().Expand());
 
@@ -192,7 +192,7 @@ DialogStyleManager::DialogStyleManager(agi::Context *context)
 	MoveImportSizer->Add(CurrentImport,1,wxEXPAND,0);
 
 	wxSizer *CurrentListSizer = new wxBoxSizer(wxHORIZONTAL);
-	CurrentList = new wxListBox(this, -1, wxDefaultPosition, wxSize(240,250), 0, NULL, wxLB_EXTENDED);
+	CurrentList = new wxListBox(this, -1, wxDefaultPosition, wxSize(240,250), 0, nullptr, wxLB_EXTENDED);
 	CurrentListSizer->Add(CurrentList,1,wxEXPAND | wxRIGHT,0);
 	CurrentListSizer->Add(make_move_buttons(this, &CurrentMoveUp, &CurrentMoveDown, &CurrentMoveTop, &CurrentMoveBottom, &CurrentSort), wxSizerFlags().Expand());
 
diff --git a/aegisub/src/dialog_style_manager.h b/aegisub/src/dialog_style_manager.h
index 1ef3ca764..b2bdfb96e 100644
--- a/aegisub/src/dialog_style_manager.h
+++ b/aegisub/src/dialog_style_manager.h
@@ -112,12 +112,12 @@ class DialogStyleManager : public wxDialog {
 	void MoveStyles(bool storage, int type);
 
 	/// Open the style editor for the given style on the script
-	/// @param style Style to edit, or NULL for new
+	/// @param style Style to edit, or nullptr for new
 	/// @param new_name Default new name for copies
 	void ShowCurrentEditor(AssStyle *style, wxString const& new_name = "");
 
 	/// Open the style editor for the given style in the storage
-	/// @param style Style to edit, or NULL for new
+	/// @param style Style to edit, or nullptr for new
 	/// @param new_name Default new name for copies
 	void ShowStorageEditor(AssStyle *style, wxString const& new_name = "");
 
diff --git a/aegisub/src/dialog_text_import.cpp b/aegisub/src/dialog_text_import.cpp
index cd231ba13..50f69d59e 100644
--- a/aegisub/src/dialog_text_import.cpp
+++ b/aegisub/src/dialog_text_import.cpp
@@ -46,7 +46,7 @@
 #include "main.h"
 
 DialogTextImport::DialogTextImport()
-: wxDialog(NULL , -1, _("Text import options"))
+: wxDialog(nullptr , -1, _("Text import options"))
 {
 	// Main controls
 	wxFlexGridSizer *fg = new wxFlexGridSizer(2, 5, 5);
diff --git a/aegisub/src/factory_manager.h b/aegisub/src/factory_manager.h
index 572caac85..76e650946 100644
--- a/aegisub/src/factory_manager.h
+++ b/aegisub/src/factory_manager.h
@@ -64,11 +64,11 @@ protected:
 	}
 
 	static func Find(std::string name) {
-		if (!classes) return NULL;
+		if (!classes) return nullptr;
 
 		iterator factory = classes->find(name);
 		if (factory != classes->end()) return factory->second.second;
-		return NULL;
+		return nullptr;
 	}
 
 public:
@@ -107,7 +107,7 @@ public:
 			return factory();
 		}
 		else {
-			return NULL;
+			return nullptr;
 		}
 	}
 
@@ -131,7 +131,7 @@ public:
 			return factory(a1);
 		}
 		else {
-			return NULL;
+			return nullptr;
 		}
 	}
 
diff --git a/aegisub/src/ffmpegsource_common.cpp b/aegisub/src/ffmpegsource_common.cpp
index e8b5cfc74..4ad7bff00 100644
--- a/aegisub/src/ffmpegsource_common.cpp
+++ b/aegisub/src/ffmpegsource_common.cpp
@@ -67,7 +67,7 @@ FFmpegSourceProvider::FFmpegSourceProvider()
 : COMInited(false, deinit_com)
 {
 #ifdef WIN32
-	HRESULT res = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
+	HRESULT res = CoInitializeEx(nullptr, COINIT_APARTMENTTHREADED);
 	if (SUCCEEDED(res))
 		COMInited = true;
 	else if (res != RPC_E_CHANGED_MODE)
@@ -95,7 +95,7 @@ static int FFMS_CC UpdateIndexingProgress(int64_t Current, int64_t Total, void *
 /// @param CacheName    The filename of the output index file
 /// @param Trackmask    A binary mask of the track numbers to index
 /// @param IgnoreDecodeErrors	True if audio decoding errors will be tolerated, false otherwise
-/// @return				Returns the index object on success, NULL otherwise
+/// @return				Returns the index object on success, nullptr otherwise
 ///
 FFMS_Index *FFmpegSourceProvider::DoIndexing(FFMS_Indexer *Indexer, const wxString &CacheName, int Trackmask, FFMS_IndexErrorHandling IndexEH) {
 	char FFMSErrMsg[1024];
@@ -115,7 +115,7 @@ FFMS_Index *FFmpegSourceProvider::DoIndexing(FFMS_Indexer *Indexer, const wxStri
 		Index = FFMS_DoIndexing(Indexer, Trackmask, FFMS_TRACKMASK_NONE, nullptr, nullptr, IndexEH, UpdateIndexingProgress, ps, &ErrInfo);
 	});
 
-	if (Index == NULL) {
+	if (Index == nullptr) {
 		MsgString.Append("Failed to index: ").Append(wxString(ErrInfo.Buffer, wxConvUTF8));
 		throw MsgString;
 	}
diff --git a/aegisub/src/font_file_lister_fontconfig.cpp b/aegisub/src/font_file_lister_fontconfig.cpp
index c5a16482a..4515ae0b4 100644
--- a/aegisub/src/font_file_lister_fontconfig.cpp
+++ b/aegisub/src/font_file_lister_fontconfig.cpp
@@ -154,7 +154,7 @@ FontFileLister::CollectionResult FontConfigFontFileLister::GetFontPaths(wxString
 	if (!FcConfigSubstitute(config, pat, FcMatchPattern)) return ret;
 
 	FcResult result;
-	agi::scoped_holder<FcFontSet*> fsorted(FcFontSort(config, pat, true, NULL, &result), FcFontSetDestroy);
+	agi::scoped_holder<FcFontSet*> fsorted(FcFontSort(config, pat, true, nullptr, &result), FcFontSetDestroy);
 	agi::scoped_holder<FcFontSet*> ffullname(MatchFullname(family.c_str(), weight, slant), FcFontSetDestroy);
 	if (!fsorted || !ffullname) return ret;
 
diff --git a/aegisub/src/gl_text.cpp b/aegisub/src/gl_text.cpp
index 7490250c7..5d81c06ff 100644
--- a/aegisub/src/gl_text.cpp
+++ b/aegisub/src/gl_text.cpp
@@ -250,7 +250,7 @@ OpenGLTextTexture::OpenGLTextTexture(OpenGLTextGlyph &glyph) {
 	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);
 
 	// Allocate texture
-	glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA8,width,height,0,GL_ALPHA,GL_UNSIGNED_BYTE,NULL);
+	glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA8,width,height,0,GL_ALPHA,GL_UNSIGNED_BYTE,nullptr);
 	if (glGetError()) throw "Internal OpenGL text renderer error: Could not allocate Text Texture";
 
 	TryToInsert(glyph);
diff --git a/aegisub/src/hotkey_data_view_model.h b/aegisub/src/hotkey_data_view_model.h
index 60f4279f9..179637d5d 100644
--- a/aegisub/src/hotkey_data_view_model.h
+++ b/aegisub/src/hotkey_data_view_model.h
@@ -36,9 +36,9 @@ class HotkeyDataViewModel : public wxDataViewModel {
 	Preferences *parent;
 	bool has_pending_changes;
 
-	/// Get the real item from the wrapper, or root if it's wrapping NULL
+	/// Get the real item from the wrapper, or root if it's wrapping nullptr
 	const HotkeyModelItem *get(wxDataViewItem const& item) const;
-	/// Get the real item from the wrapper, or root if it's wrapping NULL
+	/// Get the real item from the wrapper, or root if it's wrapping nullptr
 	HotkeyModelItem *get(wxDataViewItem const& item);
 public:
 	HotkeyDataViewModel(Preferences *parent);
diff --git a/aegisub/src/main.cpp b/aegisub/src/main.cpp
index 28494b26c..f22e7c46f 100644
--- a/aegisub/src/main.cpp
+++ b/aegisub/src/main.cpp
@@ -87,7 +87,7 @@ namespace config {
 // wxWidgets macro
 IMPLEMENT_APP(AegisubApp)
 
-static const char *LastStartupState = NULL;
+static const char *LastStartupState = nullptr;
 
 #ifdef WITH_STARTUPLOG
 #define StartupLog(a) MessageBox(0, L ## a, L"Aegisub startup log", 0)
@@ -209,11 +209,11 @@ bool AegisubApp::OnInit() {
 #endif
 
 	StartupLog("Inside OnInit");
-	frame = NULL;
+	frame = nullptr;
 	try {
 		// Initialize randomizer
 		StartupLog("Initialize random generator");
-		srand(time(NULL));
+		srand(time(nullptr));
 
 		// locale for loading options
 		StartupLog("Set initial locale");
@@ -336,7 +336,7 @@ static void UnhandledExeception(bool stackWalk) {
 #endif
 
 		// Inform user of crash.
-		wxMessageBox(wxString::Format(exception_message, filename), _("Program error"), wxOK | wxICON_ERROR | wxCENTER, NULL);
+		wxMessageBox(wxString::Format(exception_message, filename), _("Program error"), wxOK | wxICON_ERROR | wxCENTER, nullptr);
 	}
 	else if (LastStartupState) {
 #if wxUSE_STACKWALKER == 1
@@ -488,7 +488,7 @@ int AegisubApp::OnRun() {
 
 #ifdef __WXMAC__
 void AegisubApp::MacOpenFile(const wxString &filename) {
-	if (frame != NULL && !filename.empty()) {
+	if (frame != nullptr && !filename.empty()) {
 		frame->LoadSubtitles(filename);
 		wxFileName filepath(filename);
 		OPT_SET("Path/Last/Subtitles")->SetString(STD_STR(filepath.GetPath()));
diff --git a/aegisub/src/menu.cpp b/aegisub/src/menu.cpp
index 8166257d9..d69fa5e1c 100644
--- a/aegisub/src/menu.cpp
+++ b/aegisub/src/menu.cpp
@@ -119,7 +119,7 @@ struct menu_item_cmp {
 /// @brief Event dispatcher to update menus on open and handle click events
 ///
 /// Some of what the class does could be dumped off on wx, but wxEVT_MENU_OPEN
-/// is super buggy (GetMenu() often returns NULL and it outright doesn't trigger
+/// is super buggy (GetMenu() often returns nullptr and it outright doesn't trigger
 /// on submenus in many cases, and registering large numbers of wxEVT_UPDATE_UI
 /// handlers makes everything involves events unusably slow.
 class CommandManager {
diff --git a/aegisub/src/mkv_wrap.cpp b/aegisub/src/mkv_wrap.cpp
index 2065415d9..cd39901ae 100644
--- a/aegisub/src/mkv_wrap.cpp
+++ b/aegisub/src/mkv_wrap.cpp
@@ -219,7 +219,7 @@ void MatroskaWrapper::GetSubtitles(wxString const& filename, AssFile *target) {
 
 		// Progress bar
 		double totalTime = double(segInfo->Duration) / timecodeScale;
-		DialogProgress progress(NULL, _("Parsing Matroska"), _("Reading subtitles from Matroska file."));
+		DialogProgress progress(nullptr, _("Parsing Matroska"), _("Reading subtitles from Matroska file."));
 		progress.Run([&](agi::ProgressSink *ps) { read_subtitles(ps, file, &input, srt, totalTime, &parser); });
 	}
 	catch (...) {
@@ -352,7 +352,7 @@ MkvStdIO::MkvStdIO(wxString filename)
 	fp = fopen(fname.GetFullPath().utf8_str(), "rb");
 #endif
 	if (fp) {
-		setvbuf(fp, NULL, _IOFBF, CACHESIZE);
+		setvbuf(fp, nullptr, _IOFBF, CACHESIZE);
 	}
 	else {
 		throw agi::FileNotFoundError(STD_STR(filename));
diff --git a/aegisub/src/plugin_manager.cpp b/aegisub/src/plugin_manager.cpp
index fa30ecba9..e5311af1f 100644
--- a/aegisub/src/plugin_manager.cpp
+++ b/aegisub/src/plugin_manager.cpp
@@ -49,7 +49,7 @@ PluginManager::PluginManager() {
 	init = false;
 
 #ifdef WITH_AUTO4_LUA
-	lua = NULL;
+	lua = nullptr;
 #endif
 
 }
diff --git a/aegisub/src/preferences_base.cpp b/aegisub/src/preferences_base.cpp
index 07a3d775f..7bb292ce4 100644
--- a/aegisub/src/preferences_base.cpp
+++ b/aegisub/src/preferences_base.cpp
@@ -67,7 +67,7 @@ class ColourUpdater {
 	const char *name;
 	Preferences *parent;
 public:
-	ColourUpdater(const char *n = "", Preferences *p = NULL) : name(n), parent(p) { }
+	ColourUpdater(const char *n = "", Preferences *p = nullptr) : name(n), parent(p) { }
 	void operator()(wxCommandEvent& evt) {
 		ColourButton *btn = static_cast<ColourButton*>(evt.GetClientData());
 		if (btn)
diff --git a/aegisub/src/selection_controller.h b/aegisub/src/selection_controller.h
index 916dc9c25..50c7aa798 100644
--- a/aegisub/src/selection_controller.h
+++ b/aegisub/src/selection_controller.h
@@ -76,7 +76,7 @@ public:
 	/// @brief Change the active line
 	/// @param new_line Subtitle line to become the new active line
 	///
-	/// The active line may be changed to NULL, in which case there is no longer an
+	/// The active line may be changed to nullptr, in which case there is no longer an
 	/// active line.
 	///
 	/// Calling this method should only cause a change notification to be sent if
@@ -86,7 +86,7 @@ public:
 	virtual void SetActiveLine(ItemDataType new_line) = 0;
 
 	/// @brief Obtain the active line
-	/// @return The active line or NULL if there is none
+	/// @return The active line or nullptr if there is none
 	virtual ItemDataType GetActiveLine() const = 0;
 
 	/// @brief Change the selected set
diff --git a/aegisub/src/spellchecker.cpp b/aegisub/src/spellchecker.cpp
index bd9055e91..28e4ffbc3 100644
--- a/aegisub/src/spellchecker.cpp
+++ b/aegisub/src/spellchecker.cpp
@@ -44,7 +44,7 @@
 
 agi::SpellChecker *SpellCheckerFactory::GetSpellChecker() {
 	std::vector<std::string> list = GetClasses(OPT_GET("Tool/Spell Checker/Backend")->GetString());
-	if (list.empty()) return NULL;
+	if (list.empty()) return nullptr;
 
 	// Get provider
 	wxString error;
@@ -67,4 +67,4 @@ void SpellCheckerFactory::RegisterProviders() {
 #endif
 }
 
-template<> SpellCheckerFactory::map *FactoryBase<agi::SpellChecker *(*)()>::classes = NULL;
+template<> SpellCheckerFactory::map *FactoryBase<agi::SpellChecker *(*)()>::classes = nullptr;
diff --git a/aegisub/src/subtitle_format.h b/aegisub/src/subtitle_format.h
index b35f5f47d..0dc463777 100644
--- a/aegisub/src/subtitle_format.h
+++ b/aegisub/src/subtitle_format.h
@@ -131,9 +131,9 @@ public:
 	/// @param mode 0: load 1: save
 	static wxString GetWildcards(int mode);
 
-	/// Get a subtitle format that can read the given file or NULL if none can
+	/// Get a subtitle format that can read the given file or nullptr if none can
 	static const SubtitleFormat *GetReader(wxString const& filename);
-	/// Get a subtitle format that can write the given file or NULL if none can
+	/// Get a subtitle format that can write the given file or nullptr if none can
 	static const SubtitleFormat *GetWriter(wxString const& filename);
 	/// Initialize subtitle formats
 	static void LoadFormats();
diff --git a/aegisub/src/subtitle_format_ttxt.cpp b/aegisub/src/subtitle_format_ttxt.cpp
index 2f0b7141e..5574d836b 100644
--- a/aegisub/src/subtitle_format_ttxt.cpp
+++ b/aegisub/src/subtitle_format_ttxt.cpp
@@ -170,7 +170,7 @@ void TTXTSubtitleFormat::WriteFile(const AssFile *src, wxString const& filename,
 
 	// Create XML structure
 	wxXmlDocument doc;
-	wxXmlNode *root = new wxXmlNode(NULL, wxXML_ELEMENT_NODE, "TextStream");
+	wxXmlNode *root = new wxXmlNode(nullptr, wxXML_ELEMENT_NODE, "TextStream");
 	root->AddAttribute("version", "1.1");
 	doc.SetRoot(root);
 
diff --git a/aegisub/src/subtitles_provider.cpp b/aegisub/src/subtitles_provider.cpp
index ac6d39a61..426209adf 100644
--- a/aegisub/src/subtitles_provider.cpp
+++ b/aegisub/src/subtitles_provider.cpp
@@ -80,4 +80,4 @@ void SubtitlesProviderFactory::RegisterProviders() {
 #endif
 }
 
-template<> SubtitlesProviderFactory::map *FactoryBase<SubtitlesProvider *(*)(std::string)>::classes = NULL;
+template<> SubtitlesProviderFactory::map *FactoryBase<SubtitlesProvider *(*)(std::string)>::classes = nullptr;
diff --git a/aegisub/src/subtitles_provider_csri.cpp b/aegisub/src/subtitles_provider_csri.cpp
index d51ce2700..b9b39e8a5 100644
--- a/aegisub/src/subtitles_provider_csri.cpp
+++ b/aegisub/src/subtitles_provider_csri.cpp
@@ -86,7 +86,7 @@ void CSRISubtitlesProvider::LoadSubtitles(AssFile *subs) {
 		subs->SaveMemory(data);
 
 		wxMutexLocker lock(csri_mutex);
-		instance = csri_open_mem(renderer, &data[0], data.size(), NULL);
+		instance = csri_open_mem(renderer, &data[0], data.size(), nullptr);
 	}
 	// Open from disk
 	else {
@@ -98,7 +98,7 @@ void CSRISubtitlesProvider::LoadSubtitles(AssFile *subs) {
 		subs->Save(tempfile, false, false, wxSTRING_ENCODING);
 
 		wxMutexLocker lock(csri_mutex);
-		instance = csri_open_file(renderer, tempfile.utf8_str(), NULL);
+		instance = csri_open_file(renderer, tempfile.utf8_str(), nullptr);
 	}
 }
 
diff --git a/aegisub/src/subtitles_provider_libass.cpp b/aegisub/src/subtitles_provider_libass.cpp
index d4022715c..965ada76f 100644
--- a/aegisub/src/subtitles_provider_libass.cpp
+++ b/aegisub/src/subtitles_provider_libass.cpp
@@ -81,22 +81,22 @@ class FontConfigCacheThread : public wxThread {
 	ASS_Renderer *ass_renderer;
 	FontConfigCacheThread** thisPtr;
 	ExitCode Entry() {
-		const char *config_path = NULL;
+		const char *config_path = nullptr;
 #ifdef __APPLE__
 		std::string conf_path = agi::util::OSX_GetBundleResourcesDirectory() + "/etc/fonts/fonts.conf";
 		config_path = conf_path.c_str();
 #endif
 
 		if (ass_library) ass_renderer = ass_renderer_init(ass_library);
-		ass_set_fonts(ass_renderer, NULL, "Sans", 1, config_path, true);
+		ass_set_fonts(ass_renderer, nullptr, "Sans", 1, config_path, true);
 		if (ass_library) ass_renderer_done(ass_renderer);
-		*thisPtr = NULL;
+		*thisPtr = nullptr;
 		return EXIT_SUCCESS;
 	}
 public:
 	FontConfigCacheThread(ASS_Library *ass_library, FontConfigCacheThread **thisPtr)
 		: ass_library(ass_library)
-		, ass_renderer(NULL)
+		, ass_renderer(nullptr)
 		, thisPtr(thisPtr)
 	{
 		*thisPtr = this;
@@ -104,7 +104,7 @@ public:
 		Run();
 	}
 	FontConfigCacheThread(ASS_Renderer *ass_renderer, FontConfigCacheThread **thisPtr)
-		: ass_library(NULL)
+		: ass_library(nullptr)
 		, ass_renderer(ass_renderer)
 		, thisPtr(thisPtr)
 	{
@@ -133,7 +133,7 @@ LibassSubtitlesProvider::LibassSubtitlesProvider(std::string) {
 	wait_for_cache_thread(&cache_worker);
 
 	// Initialize renderer
-	ass_track = NULL;
+	ass_track = nullptr;
 	ass_renderer = ass_renderer_init(ass_library);
 	if (!ass_renderer) throw "ass_renderer_init failed";
 	ass_set_font_scale(ass_renderer, 1.);
@@ -185,7 +185,7 @@ void LibassSubtitlesProvider::DrawSubtitles(AegiVideoFrame &frame,double time) {
 	ass_set_frame_size(ass_renderer, frame.w, frame.h);
 
 	// Get frame
-	ASS_Image* img = ass_render_frame(ass_renderer, ass_track, int(time * 1000), NULL);
+	ASS_Image* img = ass_render_frame(ass_renderer, ass_track, int(time * 1000), nullptr);
 
 	// libass actually returns several alpha-masked monochrome images.
 	// Here, we loop through their linked list, get the colour of the current, and blend into the frame.
@@ -240,12 +240,12 @@ void LibassSubtitlesProvider::DrawSubtitles(AegiVideoFrame &frame,double time) {
 
 void LibassSubtitlesProvider::CacheFonts() {
 	ass_library = ass_library_init();
-	ass_set_message_cb(ass_library, msg_callback, NULL);
+	ass_set_message_cb(ass_library, msg_callback, nullptr);
 	new FontConfigCacheThread(ass_library, &cache_worker);
 }
 
 /// DOCME
 ASS_Library* LibassSubtitlesProvider::ass_library;
-FontConfigCacheThread* LibassSubtitlesProvider::cache_worker = NULL;
+FontConfigCacheThread* LibassSubtitlesProvider::cache_worker = nullptr;
 
 #endif // WITH_LIBASS
diff --git a/aegisub/src/threaded_frame_source.cpp b/aegisub/src/threaded_frame_source.cpp
index cfcacd32c..c17ff61f1 100644
--- a/aegisub/src/threaded_frame_source.cpp
+++ b/aegisub/src/threaded_frame_source.cpp
@@ -239,7 +239,7 @@ VideoProviderErrorEvent::VideoProviderErrorEvent(VideoProviderError const& err)
 	SetEventType(EVT_VIDEO_ERROR);
 }
 SubtitlesProviderErrorEvent::SubtitlesProviderErrorEvent(wxString err)
-: agi::Exception(STD_STR(err), NULL)
+: agi::Exception(STD_STR(err), nullptr)
 {
 	SetEventType(EVT_SUBTITLES_ERROR);
 }
diff --git a/aegisub/src/utils.cpp b/aegisub/src/utils.cpp
index 7716c682d..643feb177 100644
--- a/aegisub/src/utils.cpp
+++ b/aegisub/src/utils.cpp
@@ -315,7 +315,7 @@ class cache_cleaner : public wxThread {
 		do {
 			wxFileName curfn(directory, curfn_str);
 			wxDateTime curatime;
-			curfn.GetTimes(&curatime, NULL, NULL);
+			curfn.GetTimes(&curatime, nullptr, nullptr);
 			cachefiles.insert(std::make_pair(curatime.GetTicks(), curfn));
 			total_size += curfn.GetSize().GetValue();
 
diff --git a/aegisub/src/variable_data.cpp b/aegisub/src/variable_data.cpp
index 9888434d4..05165b989 100644
--- a/aegisub/src/variable_data.cpp
+++ b/aegisub/src/variable_data.cpp
@@ -44,7 +44,7 @@
 
 VariableData::VariableData() {
 	type = VARDATA_NONE;
-	value = NULL;
+	value = nullptr;
 }
 
 VariableData::~VariableData() {
@@ -64,7 +64,7 @@ void VariableData::DeleteValue() {
 		default: break;
 	}
 	type = VARDATA_NONE;
-	value = NULL;
+	value = nullptr;
 }
 
 template<class T> static inline VariableDataType get_type();
diff --git a/aegisub/src/video_context.h b/aegisub/src/video_context.h
index 5d056bfc9..e48bd3774 100644
--- a/aegisub/src/video_context.h
+++ b/aegisub/src/video_context.h
@@ -77,7 +77,7 @@ class VideoContext : public wxEvtHandler {
 
 	agi::Context *context;
 
-	/// The video provider owned by the threaded frame source, or NULL if no
+	/// The video provider owned by the threaded frame source, or nullptr if no
 	/// video is open
 	VideoProvider *videoProvider;
 
diff --git a/aegisub/src/video_out_gl.cpp b/aegisub/src/video_out_gl.cpp
index 04ce41c58..922476e48 100644
--- a/aegisub/src/video_out_gl.cpp
+++ b/aegisub/src/video_out_gl.cpp
@@ -83,7 +83,7 @@ struct VideoOutGL::TextureInfo {
 /// @param format The texture's format
 /// @return Whether the texture could be created.
 static bool TestTexture(int width, int height, GLint format) {
-	glTexImage2D(GL_PROXY_TEXTURE_2D, 0, format, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+	glTexImage2D(GL_PROXY_TEXTURE_2D, 0, format, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
 	glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0, GL_TEXTURE_INTERNAL_FORMAT, &format);
 	while (glGetError()) { } // Silently swallow all errors as we don't care why it failed if it did
 
@@ -272,7 +272,7 @@ void VideoOutGL::InitTextures(int width, int height, GLenum format, int bpp, boo
 	for (int i = 0; i < textureCount; ++i) {
 		LOG_I("video/out/gl") << "Using texture size: " << textureSizes[i].first << "x" << textureSizes[i].second;
 		CHECK_INIT_ERROR(glBindTexture(GL_TEXTURE_2D, textureIdList[i]));
-		CHECK_INIT_ERROR(glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, textureSizes[i].first, textureSizes[i].second, 0, format, GL_UNSIGNED_BYTE, NULL));
+		CHECK_INIT_ERROR(glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, textureSizes[i].first, textureSizes[i].second, 0, format, GL_UNSIGNED_BYTE, nullptr));
 		CHECK_INIT_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR));
 		CHECK_INIT_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR));
 		CHECK_INIT_ERROR(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP));
diff --git a/aegisub/src/video_provider_ffmpegsource.cpp b/aegisub/src/video_provider_ffmpegsource.cpp
index 7533bc12e..01cb00e89 100644
--- a/aegisub/src/video_provider_ffmpegsource.cpp
+++ b/aegisub/src/video_provider_ffmpegsource.cpp
@@ -58,8 +58,8 @@
 /// @brief Constructor
 /// @param filename The filename to open
 FFmpegSourceVideoProvider::FFmpegSourceVideoProvider(wxString filename) try
-: VideoSource(NULL, FFMS_DestroyVideoSource)
-, VideoInfo(NULL)
+: VideoSource(nullptr, FFMS_DestroyVideoSource)
+, VideoInfo(nullptr)
 , Width(-1)
 , Height(-1)
 , FrameNumber(-1)
@@ -112,7 +112,7 @@ void FFmpegSourceVideoProvider::LoadVideo(wxString filename) {
 		Index(FFMS_ReadIndex(CacheName.utf8_str(), &ErrInfo), FFMS_DestroyIndex);
 
 	if (Index && FFMS_IndexBelongsToFile(Index, FileNameShort.utf8_str(), &ErrInfo))
-		Index = NULL;
+		Index = nullptr;
 
 	// time to examine the index and check if the track we want is indexed
 	// technically this isn't really needed since all video tracks should always be indexed,
@@ -120,7 +120,7 @@ void FFmpegSourceVideoProvider::LoadVideo(wxString filename) {
 	if (Index && TrackNumber >= 0) {
 		FFMS_Track *TempTrackData = FFMS_GetTrackFromIndex(Index, TrackNumber);
 		if (FFMS_GetNumFrames(TempTrackData) <= 0)
-			Index = NULL;
+			Index = nullptr;
 	}
 
 	// moment of truth
@@ -224,10 +224,10 @@ void FFmpegSourceVideoProvider::LoadVideo(wxString filename) {
 
 	// get frame info data
 	FFMS_Track *FrameData = FFMS_GetTrackFromVideo(VideoSource);
-	if (FrameData == NULL)
+	if (FrameData == nullptr)
 		throw VideoOpenError("failed to get frame data");
 	const FFMS_TrackTimeBase *TimeBase = FFMS_GetTimeBase(FrameData);
-	if (TimeBase == NULL)
+	if (TimeBase == nullptr)
 		throw VideoOpenError("failed to get track time base");
 
 	const FFMS_FrameInfo *CurFrameData;
@@ -236,7 +236,7 @@ void FFmpegSourceVideoProvider::LoadVideo(wxString filename) {
 	std::vector<int> TimecodesVector;
 	for (int CurFrameNum = 0; CurFrameNum < VideoInfo->NumFrames; CurFrameNum++) {
 		CurFrameData = FFMS_GetFrameInfo(FrameData, CurFrameNum);
-		if (CurFrameData == NULL) {
+		if (CurFrameData == nullptr) {
 			throw VideoOpenError(STD_STR(wxString::Format("Couldn't get info about frame %d", CurFrameNum)));
 		}
 
@@ -261,7 +261,7 @@ const AegiVideoFrame FFmpegSourceVideoProvider::GetFrame(int n) {
 
 	// decode frame
 	const FFMS_Frame *SrcFrame = FFMS_GetFrame(VideoSource, FrameNumber, &ErrInfo);
-	if (SrcFrame == NULL) {
+	if (SrcFrame == nullptr) {
 		throw VideoDecodeError(std::string("Failed to retrieve frame: ") +  ErrInfo.Buffer);
 	}
 
diff --git a/aegisub/src/video_provider_manager.cpp b/aegisub/src/video_provider_manager.cpp
index d393165e3..94531ff0f 100644
--- a/aegisub/src/video_provider_manager.cpp
+++ b/aegisub/src/video_provider_manager.cpp
@@ -118,4 +118,4 @@ void VideoProviderFactory::RegisterProviders() {
 	Register<YUV4MPEGVideoProvider>("YUV4MPEG", true);
 }
 
-template<> VideoProviderFactory::map *FactoryBase<VideoProvider *(*)(wxString)>::classes = NULL;
+template<> VideoProviderFactory::map *FactoryBase<VideoProvider *(*)(wxString)>::classes = nullptr;
diff --git a/aegisub/src/video_provider_yuv4mpeg.cpp b/aegisub/src/video_provider_yuv4mpeg.cpp
index 4c78afd3b..51fbbe577 100644
--- a/aegisub/src/video_provider_yuv4mpeg.cpp
+++ b/aegisub/src/video_provider_yuv4mpeg.cpp
@@ -54,7 +54,7 @@
 /// @brief Constructor
 /// @param filename The filename to open
 YUV4MPEGVideoProvider::YUV4MPEGVideoProvider(wxString fname)
-: sf(NULL)
+: sf(nullptr)
 , inited(false)
 , w (0)
 , h (0)
@@ -75,7 +75,7 @@ YUV4MPEGVideoProvider::YUV4MPEGVideoProvider(wxString fname)
 		sf = fopen(filename.utf8_str(), "rb");
 #endif
 
-		if (sf == NULL) throw agi::FileNotFoundError(STD_STR(fname));
+		if (sf == nullptr) throw agi::FileNotFoundError(STD_STR(fname));
 
 		CheckFileFormat();
 
diff --git a/aegisub/src/video_slider.cpp b/aegisub/src/video_slider.cpp
index 568ceabde..36c6060de 100644
--- a/aegisub/src/video_slider.cpp
+++ b/aegisub/src/video_slider.cpp
@@ -57,7 +57,7 @@ VideoSlider::VideoSlider (wxWindow* parent, agi::Context *c)
 	SetMinSize(wxSize(20, 25));
 	SetBackgroundStyle(wxBG_STYLE_PAINT);
 
-	slots.push_back(OPT_SUB("Video/Slider/Show Keyframes", &wxWindow::Refresh, this, false, (wxRect*)NULL));
+	slots.push_back(OPT_SUB("Video/Slider/Show Keyframes", &wxWindow::Refresh, this, false, nullptr));
 	slots.push_back(c->videoController->AddSeekListener(&VideoSlider::SetValue, this));
 	slots.push_back(c->videoController->AddVideoOpenListener(&VideoSlider::VideoOpened, this));
 	slots.push_back(c->videoController->AddKeyframesListener(&VideoSlider::KeyframesChanged, this));
diff --git a/aegisub/src/visual_feature.h b/aegisub/src/visual_feature.h
index 301446909..425c43f26 100644
--- a/aegisub/src/visual_feature.h
+++ b/aegisub/src/visual_feature.h
@@ -64,7 +64,7 @@ public:
 	DraggableFeatureType type; ///< Shape of feature
 	Vector2D pos;              ///< Position of this feature
 	int layer;                 ///< Layer; Higher = above
-	AssDialogue* line;         ///< The dialogue line this feature is for; may be NULL
+	AssDialogue* line;         ///< The dialogue line this feature is for; may be nullptr
 
 	/// @brief Is the given point over this feature?
 	/// @param mouse_pos Position of the mouse
diff --git a/aegisub/src/visual_tool.cpp b/aegisub/src/visual_tool.cpp
index 67c8142d1..8ba5f2d8a 100644
--- a/aegisub/src/visual_tool.cpp
+++ b/aegisub/src/visual_tool.cpp
@@ -366,7 +366,7 @@ struct scoped_tag_parse {
 	~scoped_tag_parse() { diag->ClearBlocks(); }
 };
 
-// Find a tag's parameters in a line or return NULL if it's not found
+// Find a tag's parameters in a line or return nullptr if it's not found
 static param_vec find_tag(const AssDialogue *line, wxString tag_name) {
 	for (auto ovr : line->Blocks | agi::of_type<AssDialogueBlockOverride>()) {
 		for (auto tag : ovr->Tags) {
@@ -569,7 +569,7 @@ void VisualToolBase::SetOverride(AssDialogue* line, wxString const& tag, wxStrin
 	AssDialogueBlock *block = line->Blocks.front();
 
 	// Get current block as plain or override
-	assert(dynamic_cast<AssDialogueBlockDrawing*>(block) == NULL);
+	assert(dynamic_cast<AssDialogueBlockDrawing*>(block) == nullptr);
 
 	if (dynamic_cast<AssDialogueBlockPlain*>(block))
 		line->Text = "{" + insert + "}" + line->Text;
diff --git a/aegisub/src/visual_tool.h b/aegisub/src/visual_tool.h
index ac5126af1..b7d95c56f 100644
--- a/aegisub/src/visual_tool.h
+++ b/aegisub/src/visual_tool.h
@@ -61,7 +61,7 @@ class VisualToolBase {
 	void OnMouseCaptureLost(wxMouseCaptureLostEvent &);
 
 	/// @brief Get the dialogue line currently in the edit box
-	/// @return NULL if the line is not active on the current frame
+	/// @return nullptr if the line is not active on the current frame
 	AssDialogue *GetActiveDialogueLine();
 
 	// SubtitleSelectionListener implementation
@@ -100,7 +100,7 @@ protected:
 	VideoDisplay *parent;
 
 	bool holding; ///< Is a hold currently in progress?
-	AssDialogue *active_line; ///< Active dialogue line; NULL if it is not visible on the current frame
+	AssDialogue *active_line; ///< Active dialogue line; nullptr if it is not visible on the current frame
 	bool dragging; ///< Is a drag currently in progress?
 
 	int frame_number; ///< Current frame number
diff --git a/aegisub/src/visual_tool_drag.h b/aegisub/src/visual_tool_drag.h
index b99587e7e..6fc4d410a 100644
--- a/aegisub/src/visual_tool_drag.h
+++ b/aegisub/src/visual_tool_drag.h
@@ -41,7 +41,7 @@ class VisualToolDrag : public VisualTool<VisualToolDragDraggableFeature> {
 	wxToolBar *toolbar;
 	/// The feature last clicked on for the double-click handler
 	/// Equal to curFeature during drags; possibly different at all other times
-	/// NNULL if no features have been clicked on or the last clicked on one no
+	/// nullptr if no features have been clicked on or the last clicked on one no
 	/// longer exists
 	Feature *primary;
 	/// The last announced selection set