diff --git a/Telegram/SourceFiles/boxes/background_box.cpp b/Telegram/SourceFiles/boxes/background_box.cpp
index 9da642db0..0752658d0 100644
--- a/Telegram/SourceFiles/boxes/background_box.cpp
+++ b/Telegram/SourceFiles/boxes/background_box.cpp
@@ -18,6 +18,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "styles/style_overview.h"
 #include "styles/style_boxes.h"
 
+namespace {
+
+constexpr auto kBackgroundsInRow = 3;
+
+} // namespace
+
 class BackgroundBox::Inner
 	: public Ui::RpWidget
 	, private MTP::Sender
@@ -42,10 +48,9 @@ private:
 
 	Fn<void(int index)> _backgroundChosenCallback;
 
-	int _bgCount = 0;
-	int _rows = 0;
 	int _over = -1;
 	int _overDown = -1;
+
 	std::unique_ptr<Ui::RoundCheckbox> _check; // this is not a widget
 
 };
@@ -67,12 +72,9 @@ void BackgroundBox::prepare() {
 }
 
 void BackgroundBox::backgroundChosen(int index) {
-	if (index >= 0 && index < Auth().data().wallpapersCount()) {
-		const auto &paper = Auth().data().wallpaper(index);
-		App::main()->setChatBackground(paper);
-
-		using Update = Window::Theme::BackgroundUpdate;
-		Window::Theme::Background()->notify(Update(Update::Type::Start, !paper.id));
+	const auto &papers = Auth().data().wallpapers();
+	if (index >= 0 && index < papers.size()) {
+		App::main()->setChatBackground(papers[index]);
 	}
 	closeBox();
 }
@@ -80,24 +82,21 @@ void BackgroundBox::backgroundChosen(int index) {
 BackgroundBox::Inner::Inner(QWidget *parent) : RpWidget(parent)
 , _check(std::make_unique<Ui::RoundCheckbox>(st::overviewCheck, [=] { update(); })) {
 	_check->setChecked(true, Ui::RoundCheckbox::SetStyle::Fast);
-	if (!Auth().data().wallpapersCount()) {
-		resize(BackgroundsInRow * (st::backgroundSize.width() + st::backgroundPadding) + st::backgroundPadding, 2 * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
-		request(MTPaccount_GetWallPapers(
-			MTP_int(0)
-		)).done([=](const MTPaccount_WallPapers &result) {
-			result.match([&](const MTPDaccount_wallPapers &data) {
-				Auth().data().setWallpapers(data.vwallpapers.v);
-				updateWallpapers();
-			}, [&](const MTPDaccount_wallPapersNotModified &) {
-				LOG(("API Error: account.wallPapersNotModified received."));
-			});
-		}).send();
+	if (Auth().data().wallpapers().empty()) {
+		resize(kBackgroundsInRow * (st::backgroundSize.width() + st::backgroundPadding) + st::backgroundPadding, 2 * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
 	} else {
 		updateWallpapers();
 	}
+	request(MTPaccount_GetWallPapers(
+		MTP_int(Auth().data().wallpapersHash())
+	)).done([=](const MTPaccount_WallPapers &result) {
+		if (Auth().data().updateWallpapers(result)) {
+			updateWallpapers();
+		}
+	}).send();
 
-	subscribe(Auth().downloaderTaskFinished(), [this] { update(); });
-	subscribe(Window::Theme::Background(), [this](const Window::Theme::BackgroundUpdate &update) {
+	subscribe(Auth().downloaderTaskFinished(), [=] { update(); });
+	subscribe(Window::Theme::Background(), [=](const Window::Theme::BackgroundUpdate &update) {
 		if (update.paletteChanged()) {
 			_check->invalidateCache();
 		}
@@ -106,15 +105,16 @@ BackgroundBox::Inner::Inner(QWidget *parent) : RpWidget(parent)
 }
 
 void BackgroundBox::Inner::updateWallpapers() {
-	_bgCount = Auth().data().wallpapersCount();
-	_rows = _bgCount / BackgroundsInRow;
-	if (_bgCount % BackgroundsInRow) ++_rows;
+	const auto &papers = Auth().data().wallpapers();
+	const auto count = papers.size();
+	const auto rows = (count / kBackgroundsInRow)
+		+ (count % kBackgroundsInRow ? 1 : 0);
 
-	resize(BackgroundsInRow * (st::backgroundSize.width() + st::backgroundPadding) + st::backgroundPadding, _rows * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
-	for (int i = 0; i < BackgroundsInRow * 3; ++i) {
-		if (i >= _bgCount) break;
+	resize(kBackgroundsInRow * (st::backgroundSize.width() + st::backgroundPadding) + st::backgroundPadding, rows * (st::backgroundSize.height() + st::backgroundPadding) + st::backgroundPadding);
 
-		Auth().data().wallpaper(i).thumb->load(Data::FileOrigin());
+	const auto preload = kBackgroundsInRow * 3;
+	for (const auto &paper : papers | ranges::view::take(preload)) {
+		paper.thumb->load(Data::FileOrigin());
 	}
 }
 
@@ -122,52 +122,68 @@ void BackgroundBox::Inner::paintEvent(QPaintEvent *e) {
 	QRect r(e->rect());
 	Painter p(this);
 
-	if (_rows) {
-		for (int i = 0; i < _rows; ++i) {
-			if ((st::backgroundSize.height() + st::backgroundPadding) * (i + 1) <= r.top()) continue;
-			for (int j = 0; j < BackgroundsInRow; ++j) {
-				int index = i * BackgroundsInRow + j;
-				if (index >= _bgCount) break;
-
-				const auto &paper = Auth().data().wallpaper(index);
-				paper.thumb->load(Data::FileOrigin());
-
-				int x = st::backgroundPadding + j * (st::backgroundSize.width() + st::backgroundPadding);
-				int y = st::backgroundPadding + i * (st::backgroundSize.height() + st::backgroundPadding);
-
-				const auto &pix = paper.thumb->pix(
-					Data::FileOrigin(),
-					st::backgroundSize.width(),
-					st::backgroundSize.height());
-				p.drawPixmap(x, y, pix);
-
-				if (paper.id == Window::Theme::Background()->id()) {
-					auto checkLeft = x + st::backgroundSize.width() - st::overviewCheckSkip - st::overviewCheck.size;
-					auto checkTop = y + st::backgroundSize.height() - st::overviewCheckSkip - st::overviewCheck.size;
-					_check->paint(p, getms(), checkLeft, checkTop, width());
-				}
-			}
-		}
-	} else {
+	const auto &papers = Auth().data().wallpapers();
+	if (papers.empty()) {
 		p.setFont(st::noContactsFont);
 		p.setPen(st::noContactsColor);
 		p.drawText(QRect(0, 0, width(), st::noContactsHeight), lang(lng_contacts_loading), style::al_center);
+		return;
+	}
+	auto row = 0;
+	auto column = 0;
+	for (const auto &paper : papers) {
+		const auto increment = gsl::finally([&] {
+			++column;
+			if (column == kBackgroundsInRow) {
+				column = 0;
+				++row;
+			}
+		});
+		if ((st::backgroundSize.height() + st::backgroundPadding) * (row + 1) <= r.top()) {
+			continue;
+		}
+
+		paper.thumb->load(Data::FileOrigin());
+
+		int x = st::backgroundPadding + column * (st::backgroundSize.width() + st::backgroundPadding);
+		int y = st::backgroundPadding + row * (st::backgroundSize.height() + st::backgroundPadding);
+
+		const auto &pix = paper.thumb->pix(
+			Data::FileOrigin(),
+			st::backgroundSize.width(),
+			st::backgroundSize.height());
+		p.drawPixmap(x, y, pix);
+
+		if (paper.id == Window::Theme::Background()->id()) {
+			auto checkLeft = x + st::backgroundSize.width() - st::overviewCheckSkip - st::overviewCheck.size;
+			auto checkTop = y + st::backgroundSize.height() - st::overviewCheckSkip - st::overviewCheck.size;
+			_check->paint(p, getms(), checkLeft, checkTop, width());
+		}
 	}
 }
 
 void BackgroundBox::Inner::mouseMoveEvent(QMouseEvent *e) {
-	int x = e->pos().x(), y = e->pos().y();
-	int row = int((y - st::backgroundPadding) / (st::backgroundSize.height() + st::backgroundPadding));
-	if (y - row * (st::backgroundSize.height() + st::backgroundPadding) > st::backgroundPadding + st::backgroundSize.height()) row = _rows + 1;
-
-	int col = int((x - st::backgroundPadding) / (st::backgroundSize.width() + st::backgroundPadding));
-	if (x - col * (st::backgroundSize.width() + st::backgroundPadding) > st::backgroundPadding + st::backgroundSize.width()) row = _rows + 1;
-
-	int newOver = row * BackgroundsInRow + col;
-	if (newOver >= _bgCount) newOver = -1;
-	if (newOver != _over) {
+	const auto newOver = [&] {
+		const auto x = e->pos().x();
+		const auto y = e->pos().y();
+		const auto width = st::backgroundSize.width();
+		const auto height = st::backgroundSize.height();
+		const auto skip = st::backgroundPadding;
+		const auto row = int((y - skip) / (height + skip));
+		const auto column = int((x - skip) / (width + skip));
+		if (y - row * (height + skip) > skip + height) {
+			return -1;
+		} else if (x - column * (width + skip) > skip + width) {
+			return -1;
+		}
+		const auto result = row * kBackgroundsInRow + column;
+		return (result < Auth().data().wallpapers().size()) ? result : -1;
+	}();
+	if (_over != newOver) {
 		_over = newOver;
-		setCursor((_over >= 0 || _overDown >= 0) ? style::cur_pointer : style::cur_default);
+		setCursor((_over >= 0 || _overDown >= 0)
+			? style::cur_pointer
+			: style::cur_default);
 	}
 }
 
diff --git a/Telegram/SourceFiles/config.h b/Telegram/SourceFiles/config.h
index 7ff666efe..bbf97ebeb 100644
--- a/Telegram/SourceFiles/config.h
+++ b/Telegram/SourceFiles/config.h
@@ -81,7 +81,6 @@ enum {
 	WebPageUserId = 701000,
 
 	CacheBackgroundTimeout = 3000, // cache background scaled image after 3s
-	BackgroundsInRow = 3,
 
 	UpdateDelayConstPart = 8 * 3600, // 8 hour min time between update check requests
 	UpdateDelayRandPart = 8 * 3600, // 8 hour max - min time between update check requests
diff --git a/Telegram/SourceFiles/data/data_document.cpp b/Telegram/SourceFiles/data/data_document.cpp
index fa8fb29a9..0cd774e72 100644
--- a/Telegram/SourceFiles/data/data_document.cpp
+++ b/Telegram/SourceFiles/data/data_document.cpp
@@ -478,10 +478,13 @@ void DocumentData::setattributes(const QVector<MTPDocumentAttribute> &attributes
 			auto &d = attributes[i].c_documentAttributeImageSize();
 			dimensions = QSize(d.vw.v, d.vh.v);
 		} break;
-		case mtpc_documentAttributeAnimated: if (type == FileDocument || type == StickerDocument || type == VideoDocument) {
-			type = AnimatedDocument;
-			_additional = nullptr;
-		} break;
+		case mtpc_documentAttributeAnimated:
+			if (type == FileDocument
+				|| type == StickerDocument
+				|| type == VideoDocument) {
+				type = AnimatedDocument;
+				_additional = nullptr;
+			} break;
 		case mtpc_documentAttributeSticker: {
 			auto &d = attributes[i].c_documentAttributeSticker();
 			if (type == FileDocument) {
@@ -490,7 +493,8 @@ void DocumentData::setattributes(const QVector<MTPDocumentAttribute> &attributes
 			}
 			if (sticker()) {
 				sticker()->alt = qs(d.valt);
-				if (sticker()->set.type() != mtpc_inputStickerSetID || d.vstickerset.type() == mtpc_inputStickerSetID) {
+				if (sticker()->set.type() != mtpc_inputStickerSetID
+					|| d.vstickerset.type() == mtpc_inputStickerSetID) {
 					sticker()->set = d.vstickerset;
 				}
 			}
@@ -498,7 +502,9 @@ void DocumentData::setattributes(const QVector<MTPDocumentAttribute> &attributes
 		case mtpc_documentAttributeVideo: {
 			auto &d = attributes[i].c_documentAttributeVideo();
 			if (type == FileDocument) {
-				type = d.is_round_message() ? RoundVideoDocument : VideoDocument;
+				type = d.is_round_message()
+					? RoundVideoDocument
+					: VideoDocument;
 			}
 			_duration = d.vduration.v;
 			_supportsStreaming = d.is_supports_streaming();
@@ -568,6 +574,24 @@ void DocumentData::setattributes(const QVector<MTPDocumentAttribute> &attributes
 	validateGoodThumbnail();
 }
 
+bool DocumentData::checkWallPaperProperties() {
+	if (type != FileDocument
+		|| !thumb
+		|| !dimensions.width()
+		|| !dimensions.height()
+		|| dimensions.width() > Storage::kMaxWallPaperDimension
+		|| dimensions.height() > Storage::kMaxWallPaperDimension
+		|| size > Storage::kMaxWallPaperInMemory) {
+		return false;
+	}
+	type = WallPaperDocument;
+	return true;
+}
+
+bool DocumentData::isWallPaper() const {
+	return (type == WallPaperDocument);
+}
+
 Storage::Cache::Key DocumentData::goodThumbnailCacheKey() const {
 	return Data::DocumentThumbCacheKey(_dc, id);
 }
@@ -610,7 +634,8 @@ void DocumentData::setGoodThumbnail(QImage &&image, QByteArray &&bytes) {
 bool DocumentData::saveToCache() const {
 	return (type == StickerDocument && size < Storage::kMaxStickerInMemory)
 		|| (isAnimation() && size < Storage::kMaxAnimationInMemory)
-		|| (isVoiceMessage() && size < Storage::kMaxVoiceInMemory);
+		|| (isVoiceMessage() && size < Storage::kMaxVoiceInMemory)
+		|| (type == WallPaperDocument);
 }
 
 void DocumentData::unload() {
diff --git a/Telegram/SourceFiles/data/data_document.h b/Telegram/SourceFiles/data/data_document.h
index 716960678..bb91c7a9d 100644
--- a/Telegram/SourceFiles/data/data_document.h
+++ b/Telegram/SourceFiles/data/data_document.h
@@ -122,7 +122,7 @@ public:
 		FilePathResolveType type = FilePathResolveCached,
 		bool forceSavingAs = false) const;
 
-	bool saveToCache() const;
+	[[nodiscard]] bool saveToCache() const;
 
 	void performActionOnLoad();
 
@@ -158,6 +158,8 @@ public:
 	void setData(const QByteArray &data) {
 		_data = data;
 	}
+	bool checkWallPaperProperties();
+	bool isWallPaper() const;
 
 	bool hasGoodStickerThumb() const;
 
diff --git a/Telegram/SourceFiles/data/data_session.cpp b/Telegram/SourceFiles/data/data_session.cpp
index e1919bc9f..a12370670 100644
--- a/Telegram/SourceFiles/data/data_session.cpp
+++ b/Telegram/SourceFiles/data/data_session.cpp
@@ -44,6 +44,7 @@ namespace Data {
 namespace {
 
 constexpr auto kMaxNotifyCheckDelay = 24 * 3600 * TimeMs(1000);
+constexpr auto kMaxWallpaperSize = 10 * 1024 * 1024;
 
 using ViewElement = HistoryView::Element;
 
@@ -3055,40 +3056,52 @@ PeerData *Session::proxyPromoted() const {
 	return _proxyPromoted;
 }
 
-int Session::wallpapersCount() const {
-	return _wallpapers.size();
+bool Session::updateWallpapers(const MTPaccount_WallPapers &data) {
+	return data.match([&](const MTPDaccount_wallPapers &data) {
+		setWallpapers(data.vwallpapers.v, data.vhash.v);
+		return true;
+	}, [&](const MTPDaccount_wallPapersNotModified &) {
+		return false;
+	});
 }
 
-const WallPaper &Session::wallpaper(int index) const {
-	Expects(index >= 0 && index < _wallpapers.size());
+void Session::setWallpapers(const QVector<MTPWallPaper> &data, int32 hash) {
+	_wallpapersHash = hash;
 
-	return _wallpapers[index];
-}
-
-void Session::setWallpapers(const QVector<MTPWallPaper> &data) {
 	_wallpapers.clear();
 	_wallpapers.reserve(data.size() + 1);
 
-	auto oldBackground = Images::Create(qsl(":/gui/art/bg_initial.jpg"), "JPG");
-	_wallpapers.push_back({
-		Window::Theme::kInitialBackground,
-		oldBackground,
-		oldBackground
-	});
+	const auto oldBackground = Images::Create(
+		qsl(":/gui/art/bg_initial.jpg"),
+		"JPG");
+	if (oldBackground) {
+		_wallpapers.push_back({
+			Window::Theme::kInitialBackground,
+			oldBackground
+		});
+	}
 	for (const auto &paper : data) {
 		paper.match([&](const MTPDwallPaper &paper) {
-			const auto document = Auth().data().document(paper.vdocument);
-			if (document->thumb) {
+			const auto document = this->document(paper.vdocument);
+			if (document->checkWallPaperProperties()) {
 				_wallpapers.push_back({
-					paper.vid.v ? int32(paper.vid.v) : INT_MAX,
-					document->thumb,
+					paper.vid.v,
 					document->thumb,
+					document,
 				});
 			}
 		});
 	}
 }
 
+const std::vector<WallPaper> &Session::wallpapers() const {
+	return _wallpapers;
+}
+
+int32 Session::wallpapersHash() const {
+	return _wallpapersHash;
+}
+
 void Session::clearLocalStorage() {
 	clear();
 
diff --git a/Telegram/SourceFiles/data/data_session.h b/Telegram/SourceFiles/data/data_session.h
index beffba7a6..9082ff311 100644
--- a/Telegram/SourceFiles/data/data_session.h
+++ b/Telegram/SourceFiles/data/data_session.h
@@ -15,6 +15,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/history_location_manager.h"
 #include "base/timer.h"
 
+class Image;
 class HistoryItem;
 class BoxContent;
 struct WebPageCollage;
@@ -51,9 +52,9 @@ enum class FeedUpdateFlag;
 struct FeedUpdate;
 
 struct WallPaper {
-	int32 id = 0;
+	WallPaperId id = WallPaperId();
 	ImagePtr thumb;
-	ImagePtr full;
+	DocumentData *document = nullptr;
 };
 
 class Session final {
@@ -530,9 +531,9 @@ public:
 		return _groups;
 	}
 
-	int wallpapersCount() const;
-	const WallPaper &wallpaper(int index) const;
-	void setWallpapers(const QVector<MTPWallPaper> &data);
+	bool updateWallpapers(const MTPaccount_WallPapers &data);
+	const std::vector<WallPaper> &wallpapers() const;
+	int32 wallpapersHash() const;
 
 	void clearLocalStorage();
 
@@ -639,7 +640,6 @@ private:
 	void unmuteByFinished();
 	void unmuteByFinishedDelayed(TimeMs delay);
 	void updateNotifySettingsLocal(not_null<PeerData*> peer);
-	void sendNotifySettingsUpdates();
 
 	template <typename Method>
 	void enumerateItemViews(
@@ -653,6 +653,8 @@ private:
 
 	void step_typings(TimeMs ms, bool timer);
 
+	void setWallpapers(const QVector<MTPWallPaper> &data, int32 hash);
+
 	not_null<AuthSession*> _session;
 
 	Storage::DatabasePointer _cache;
@@ -797,6 +799,7 @@ private:
 	rpl::event_stream<SendActionAnimationUpdate> _sendActionAnimationUpdate;
 
 	std::vector<WallPaper> _wallpapers;
+	int32 _wallpapersHash = 0;
 
 	rpl::lifetime _lifetime;
 
diff --git a/Telegram/SourceFiles/data/data_types.h b/Telegram/SourceFiles/data/data_types.h
index e325d8ff3..826dbc00e 100644
--- a/Telegram/SourceFiles/data/data_types.h
+++ b/Telegram/SourceFiles/data/data_types.h
@@ -270,6 +270,7 @@ using DocumentId = uint64;
 using WebPageId = uint64;
 using GameId = uint64;
 using PollId = uint64;
+using WallPaperId = uint64;
 constexpr auto CancelledWebPageId = WebPageId(0xFFFFFFFFFFFFFFFFULL);
 
 using PreparedPhotoThumbs = QMap<char, QImage>;
@@ -309,6 +310,7 @@ enum DocumentType {
 	AnimatedDocument = 4,
 	VoiceDocument = 5,
 	RoundVideoDocument = 6,
+	WallPaperDocument = 7,
 };
 
 using MediaKey = QPair<uint64, uint64>;
diff --git a/Telegram/SourceFiles/data/data_web_page.cpp b/Telegram/SourceFiles/data/data_web_page.cpp
index 4c8af1521..4a783f9a8 100644
--- a/Telegram/SourceFiles/data/data_web_page.cpp
+++ b/Telegram/SourceFiles/data/data_web_page.cpp
@@ -133,6 +133,7 @@ WebPageType ParseWebPageType(const MTPDwebPage &page) {
 	if (type == qstr("photo")) return WebPageType::Photo;
 	if (type == qstr("video")) return WebPageType::Video;
 	if (type == qstr("profile")) return WebPageType::Profile;
+	if (type == qstr("telegram_wallpaper")) return WebPageType::WallPaper;
 	return page.has_cached_page()
 		? WebPageType::ArticleWithIV
 		: WebPageType::Article;
@@ -217,6 +218,10 @@ bool WebPageData::applyChanges(
 	pendingTill = newPendingTill;
 	++version;
 
+	if (type == WebPageType::WallPaper) {
+		document->checkWallPaperProperties();
+	}
+
 	replaceDocumentGoodThumbnail();
 
 	return true;
diff --git a/Telegram/SourceFiles/data/data_web_page.h b/Telegram/SourceFiles/data/data_web_page.h
index 931128ca8..30fb70348 100644
--- a/Telegram/SourceFiles/data/data_web_page.h
+++ b/Telegram/SourceFiles/data/data_web_page.h
@@ -14,6 +14,7 @@ enum class WebPageType {
 	Photo,
 	Video,
 	Profile,
+	WallPaper,
 	Article,
 	ArticleWithIV,
 };
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index 27a059aff..b93f43b9d 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -31,6 +31,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/toast/toast.h"
 #include "ui/widgets/dropdown_menu.h"
 #include "ui/image/image.h"
+#include "ui/image/image_source.h"
 #include "ui/focus_persister.h"
 #include "ui/resize_area.h"
 #include "ui/text_options.h"
@@ -1414,8 +1415,16 @@ void MainWidget::updateScrollColors() {
 
 void MainWidget::setChatBackground(const Data::WallPaper &background) {
 	_background = std::make_unique<Data::WallPaper>(background);
-	_background->full->loadEvenCancelled(Data::FileOrigin());
+	if (_background->document) {
+		_background->document->save(Data::FileOrigin(), QString());
+	} else if (_background->thumb) {
+		_background->thumb->loadEvenCancelled(Data::FileOrigin());
+	}
 	checkChatBackground();
+
+	const auto tile = (background.id == Window::Theme::kInitialBackground);
+	using Update = Window::Theme::BackgroundUpdate;
+	Window::Theme::Background()->notify(Update(Update::Type::Start, tile));
 }
 
 bool MainWidget::chatBackgroundLoading() {
@@ -1424,27 +1433,65 @@ bool MainWidget::chatBackgroundLoading() {
 
 float64 MainWidget::chatBackgroundProgress() const {
 	if (_background) {
-		return _background->full->progress();
+		if (_background->document) {
+			return _background->document->progress();
+		} else if (_background->thumb) {
+			return _background->thumb->progress();
+		}
 	}
 	return 1.;
 }
 
 void MainWidget::checkChatBackground() {
-	if (_background) {
-		if (_background->full->loaded()) {
-			if (_background->full->isNull()) {
-				Window::Theme::Background()->setImage(Window::Theme::kDefaultBackground);
-			} else if (false
-				|| _background->id == Window::Theme::kInitialBackground
-				|| _background->id == Window::Theme::kDefaultBackground) {
-				Window::Theme::Background()->setImage(_background->id);
-			} else {
-				Window::Theme::Background()->setImage(_background->id, _background->full->pix(Data::FileOrigin()).toImage());
-			}
-			_background = nullptr;
-			crl::on_main(this, [=] { update(); });
-		}
+	using namespace Window::Theme;
+
+	if (!_background) {
+		return;
 	}
+	const auto document = _background->document;
+	if (document && !document->loaded()) {
+		return;
+	} else if (!document && !_background->thumb->loaded()) {
+		return;
+	}
+
+	auto image = [&] {
+		if (!document) {
+			const auto &thumb = _background->thumb;
+			return thumb
+				? thumb->pixNoCache(Data::FileOrigin()).toImage()
+				: QImage();
+		}
+		auto bytes = document->data();
+		auto format = QByteArray();
+		const auto path = document->filepath();
+		if (bytes.isEmpty()) {
+			QFile f(document->filepath());
+			if (f.size() <= App::kImageSizeLimit
+				&& f.open(QIODevice::ReadOnly)) {
+				bytes = f.readAll();
+			}
+		}
+		return bytes.isEmpty()
+			? QImage()
+			: App::readImage(bytes, &format, false, nullptr);
+	}();
+
+	if (image.isNull()) {
+		Background()->setImage(kDefaultBackground);
+	} else if (false
+		|| _background->id == kInitialBackground
+		|| _background->id == kDefaultBackground) {
+		Background()->setImage(_background->id);
+	} else {
+		Background()->setImage(
+			_background->id,
+			std::move(image));
+	}
+	const auto tile = (_background->id == kInitialBackground);
+	Background()->setTile(tile);
+	_background = nullptr;
+	crl::on_main(this, [=] { update(); });
 }
 
 ImagePtr MainWidget::newBackgroundThumb() {
@@ -1483,14 +1530,14 @@ void MainWidget::setInnerFocus() {
 
 void MainWidget::scheduleViewIncrement(HistoryItem *item) {
 	PeerData *peer = item->history()->peer;
-	ViewsIncrement::iterator i = _viewsIncremented.find(peer);
+	auto i = _viewsIncremented.find(peer);
 	if (i != _viewsIncremented.cend()) {
 		if (i.value().contains(item->id)) return;
 	} else {
 		i = _viewsIncremented.insert(peer, ViewsIncrementMap());
 	}
 	i.value().insert(item->id, true);
-	ViewsIncrement::iterator j = _viewsToIncrement.find(peer);
+	auto j = _viewsToIncrement.find(peer);
 	if (j == _viewsToIncrement.cend()) {
 		j = _viewsToIncrement.insert(peer, ViewsIncrementMap());
 		_viewsIncrementTimer.start(SendViewsTimeout);
@@ -1499,7 +1546,7 @@ void MainWidget::scheduleViewIncrement(HistoryItem *item) {
 }
 
 void MainWidget::onViewsIncrement() {
-	for (ViewsIncrement::iterator i = _viewsToIncrement.begin(); i != _viewsToIncrement.cend();) {
+	for (auto i = _viewsToIncrement.begin(); i != _viewsToIncrement.cend();) {
 		if (_viewsIncrementRequests.contains(i.key())) {
 			++i;
 			continue;
@@ -1519,7 +1566,7 @@ void MainWidget::onViewsIncrement() {
 void MainWidget::viewsIncrementDone(QVector<MTPint> ids, const MTPVector<MTPint> &result, mtpRequestId req) {
 	auto &v = result.v;
 	if (ids.size() == v.size()) {
-		for (ViewsIncrementRequests::iterator i = _viewsIncrementRequests.begin(); i != _viewsIncrementRequests.cend(); ++i) {
+		for (auto i = _viewsIncrementRequests.begin(); i != _viewsIncrementRequests.cend(); ++i) {
 			if (i.value() == req) {
 				PeerData *peer = i.key();
 				ChannelId channel = peerToChannel(peer->id);
@@ -1541,7 +1588,7 @@ void MainWidget::viewsIncrementDone(QVector<MTPint> ids, const MTPVector<MTPint>
 bool MainWidget::viewsIncrementFail(const RPCError &error, mtpRequestId req) {
 	if (MTP::isDefaultHandledError(error)) return false;
 
-	for (ViewsIncrementRequests::iterator i = _viewsIncrementRequests.begin(); i != _viewsIncrementRequests.cend(); ++i) {
+	for (auto i = _viewsIncrementRequests.begin(); i != _viewsIncrementRequests.cend(); ++i) {
 		if (i.value() == req) {
 			_viewsIncrementRequests.erase(i);
 			break;
@@ -2274,7 +2321,9 @@ void MainWidget::animationCallback() {
 }
 
 void MainWidget::paintEvent(QPaintEvent *e) {
-	if (_background) checkChatBackground();
+	if (_background) {
+		checkChatBackground();
+	}
 
 	Painter p(this);
 	auto progress = _a_show.current(getms(), 1.);
@@ -3059,25 +3108,19 @@ void MainWidget::ptsWaiterStartTimerFor(ChannelData *channel, int32 ms) {
 }
 
 void MainWidget::failDifferenceStartTimerFor(ChannelData *channel) {
-	int32 ms = 0;
-	ChannelFailDifferenceTimeout::iterator i;
-	if (channel) {
-		i = _channelFailDifferenceTimeout.find(channel);
-		if (i == _channelFailDifferenceTimeout.cend()) {
-			i = _channelFailDifferenceTimeout.insert(channel, 1);
+	auto &timeout = [&]() -> int32& {
+		if (!channel) {
+			return _failDifferenceTimeout;
 		}
-		ms = i.value() * 1000;
-	} else {
-		ms = _failDifferenceTimeout * 1000;
-	}
-	if (getDifferenceTimeChanged(channel, ms, _channelGetDifferenceTimeAfterFail, _getDifferenceTimeAfterFail)) {
+		const auto i = _channelFailDifferenceTimeout.find(channel);
+		return (i == _channelFailDifferenceTimeout.end())
+			? _channelFailDifferenceTimeout.insert(channel, 1).value()
+			: i.value();
+	}();
+	if (getDifferenceTimeChanged(channel, timeout * 1000, _channelGetDifferenceTimeAfterFail, _getDifferenceTimeAfterFail)) {
 		onGetDifferenceTimeAfterFail();
 	}
-	if (channel) {
-		if (i.value() < 64) i.value() *= 2;
-	} else {
-		if (_failDifferenceTimeout < 64) _failDifferenceTimeout *= 2;
-	}
+	if (timeout < 64) timeout *= 2;
 }
 
 bool MainWidget::ptsUpdateAndApply(int32 pts, int32 ptsCount, const MTPUpdates &updates) {
diff --git a/Telegram/SourceFiles/mainwidget.h b/Telegram/SourceFiles/mainwidget.h
index 6abab911e..a25604631 100644
--- a/Telegram/SourceFiles/mainwidget.h
+++ b/Telegram/SourceFiles/mainwidget.h
@@ -523,8 +523,7 @@ private:
 	bool _isIdle = false;
 
 	int32 _failDifferenceTimeout = 1; // growing timeout for getDifference calls, if it fails
-	typedef QMap<ChannelData*, int32> ChannelFailDifferenceTimeout;
-	ChannelFailDifferenceTimeout _channelFailDifferenceTimeout; // growing timeout for getChannelDifference calls, if it fails
+	QMap<ChannelData*, int32> _channelFailDifferenceTimeout; // growing timeout for getChannelDifference calls, if it fails
 	SingleTimer _failDifferenceTimer;
 
 	TimeMs _lastUpdateTime = 0;
@@ -538,13 +537,10 @@ private:
 
 	PhotoData *_deletingPhoto = nullptr;
 
-	typedef QMap<MsgId, bool> ViewsIncrementMap;
-	typedef QMap<PeerData*, ViewsIncrementMap> ViewsIncrement;
-	ViewsIncrement _viewsIncremented, _viewsToIncrement;
-	typedef QMap<PeerData*, mtpRequestId> ViewsIncrementRequests;
-	ViewsIncrementRequests _viewsIncrementRequests;
-	typedef QMap<mtpRequestId, PeerData*> ViewsIncrementByRequest;
-	ViewsIncrementByRequest _viewsIncrementByRequest;
+	using ViewsIncrementMap = QMap<MsgId, bool>;
+	QMap<PeerData*, ViewsIncrementMap> _viewsIncremented, _viewsToIncrement;
+	QMap<PeerData*, mtpRequestId> _viewsIncrementRequests;
+	QMap<mtpRequestId, PeerData*> _viewsIncrementByRequest;
 	SingleTimer _viewsIncrementTimer;
 
 	std::unique_ptr<Data::WallPaper> _background;
diff --git a/Telegram/SourceFiles/storage/file_download.h b/Telegram/SourceFiles/storage/file_download.h
index 2c1a41023..d2ff66594 100644
--- a/Telegram/SourceFiles/storage/file_download.h
+++ b/Telegram/SourceFiles/storage/file_download.h
@@ -19,7 +19,9 @@ struct Key;
 constexpr auto kMaxFileInMemory = 10 * 1024 * 1024; // 10 MB max file could be hold in memory
 constexpr auto kMaxVoiceInMemory = 2 * 1024 * 1024; // 2 MB audio is hold in memory and auto loaded
 constexpr auto kMaxStickerInMemory = 2 * 1024 * 1024; // 2 MB stickers hold in memory, auto loaded and displayed inline
+constexpr auto kMaxWallPaperInMemory = kMaxFileInMemory;
 constexpr auto kMaxAnimationInMemory = kMaxFileInMemory; // 10 MB gif and mp4 animations held in memory while playing
+constexpr auto kMaxWallPaperDimension = 4096; // 4096x4096 is max area.
 
 class Downloader final {
 public:
diff --git a/Telegram/SourceFiles/storage/localstorage.cpp b/Telegram/SourceFiles/storage/localstorage.cpp
index 55cf0b712..ea03abdc4 100644
--- a/Telegram/SourceFiles/storage/localstorage.cpp
+++ b/Telegram/SourceFiles/storage/localstorage.cpp
@@ -3956,7 +3956,7 @@ void readSavedGifs() {
 	}
 }
 
-void writeBackground(int32 id, const QImage &img) {
+void writeBackground(WallPaperId id, const QImage &img) {
 	if (!_working() || !_backgroundCanWrite) {
 		return;
 	}
@@ -3982,10 +3982,13 @@ void writeBackground(int32 id, const QImage &img) {
 		_writeMap(WriteMapWhen::Fast);
 	}
 	quint32 size = sizeof(qint32)
-		+ sizeof(quint32)
-		+ (bmp.isEmpty() ? 0 : (sizeof(quint32) + bmp.size()));
+		+ sizeof(quint64)
+		+ Serialize::bytearraySize(bmp);
 	EncryptedDescriptor data(size);
-	data.stream << qint32(id) << bmp;
+	data.stream
+		<< qint32(Window::Theme::internal::kLegacyBackgroundId)
+		<< quint64(id)
+		<< bmp;
 
 	FileWriteDescriptor file(backgroundKey);
 	file.writeEncrypted(data);
@@ -4007,8 +4010,15 @@ bool readBackground() {
 	}
 
 	QByteArray bmpData;
-	qint32 id;
-	bg.stream >> id >> bmpData;
+	qint32 legacyId;
+	quint64 id;
+	bg.stream >> legacyId;
+	if (legacyId == Window::Theme::internal::kLegacyBackgroundId) {
+		bg.stream >> id;
+	} else {
+		id = Window::Theme::internal::FromLegacyBackgroundId(legacyId);
+	}
+	bg.stream >> bmpData;
 	auto oldEmptyImage = (bg.stream.status() != QDataStream::Ok);
 	if (oldEmptyImage
 		|| id == Window::Theme::kInitialBackground
diff --git a/Telegram/SourceFiles/storage/localstorage.h b/Telegram/SourceFiles/storage/localstorage.h
index ef56b217b..6f8f74686 100644
--- a/Telegram/SourceFiles/storage/localstorage.h
+++ b/Telegram/SourceFiles/storage/localstorage.h
@@ -136,7 +136,7 @@ void writeSavedGifs();
 void readSavedGifs();
 int32 countSavedGifsHash();
 
-void writeBackground(int32 id, const QImage &img);
+void writeBackground(WallPaperId id, const QImage &img);
 bool readBackground();
 
 void writeTheme(const Window::Theme::Saved &saved);
diff --git a/Telegram/SourceFiles/window/themes/window_theme.cpp b/Telegram/SourceFiles/window/themes/window_theme.cpp
index 047e94d29..50fbe1489 100644
--- a/Telegram/SourceFiles/window/themes/window_theme.cpp
+++ b/Telegram/SourceFiles/window/themes/window_theme.cpp
@@ -389,7 +389,7 @@ void ChatBackground::start() {
 	}
 }
 
-void ChatBackground::setImage(int32 id, QImage &&image) {
+void ChatBackground::setImage(WallPaperId id, QImage &&image) {
 	auto needResetAdjustable = (id == kDefaultBackground)
 		&& (_id != kDefaultBackground)
 		&& !nightMode()
@@ -528,7 +528,7 @@ void ChatBackground::adjustPaletteUsingBackground(const QImage &img) {
 	}
 }
 
-int32 ChatBackground::id() const {
+WallPaperId ChatBackground::id() const {
 	return _id;
 }
 
diff --git a/Telegram/SourceFiles/window/themes/window_theme.h b/Telegram/SourceFiles/window/themes/window_theme.h
index 7169cb2bb..87dcd1e76 100644
--- a/Telegram/SourceFiles/window/themes/window_theme.h
+++ b/Telegram/SourceFiles/window/themes/window_theme.h
@@ -11,17 +11,22 @@ namespace Window {
 namespace Theme {
 namespace internal {
 
-constexpr int32 kUninitializedBackground = -999;
-constexpr int32 kTestingThemeBackground = -666;
-constexpr int32 kTestingDefaultBackground = -665;
-constexpr int32 kTestingEditorBackground = -664;
+constexpr auto FromLegacyBackgroundId(int32 legacyId) -> WallPaperId {
+	return uint64(0xFFFFFFFF00000000ULL) | uint64(uint32(legacyId));
+}
+
+constexpr auto kUninitializedBackground = FromLegacyBackgroundId(-999);
+constexpr auto kTestingThemeBackground = FromLegacyBackgroundId(-666);
+constexpr auto kTestingDefaultBackground = FromLegacyBackgroundId(-665);
+constexpr auto kTestingEditorBackground = FromLegacyBackgroundId(-664);
+constexpr auto kLegacyBackgroundId = int32(-111);
 
 } // namespace internal
 
-constexpr int32 kThemeBackground = -2;
-constexpr int32 kCustomBackground = -1;
-constexpr int32 kInitialBackground = 0;
-constexpr int32 kDefaultBackground = 105;
+constexpr auto kThemeBackground = internal::FromLegacyBackgroundId(-2);
+constexpr auto kCustomBackground = internal::FromLegacyBackgroundId(-1);
+constexpr auto kInitialBackground = internal::FromLegacyBackgroundId(0);
+constexpr auto kDefaultBackground = internal::FromLegacyBackgroundId(105);
 
 struct Cached {
 	QByteArray colors;
@@ -98,7 +103,7 @@ public:
 
 	// This method is setting the default (themed) image if none was set yet.
 	void start();
-	void setImage(int32 id, QImage &&image = QImage());
+	void setImage(WallPaperId id, QImage &&image = QImage());
 	void setTile(bool tile);
 	void setTileDayValue(bool tile);
 	void setTileNightValue(bool tile);
@@ -111,7 +116,7 @@ public:
 	void setTestingDefaultTheme();
 	void revert();
 
-	int32 id() const;
+	WallPaperId id() const;
 	const QPixmap &pixmap() const {
 		return _pixmap;
 	}
@@ -152,7 +157,7 @@ private:
 	friend void KeepApplied();
 	friend bool IsNonDefaultBackground();
 
-	int32 _id = internal::kUninitializedBackground;
+	WallPaperId _id = internal::kUninitializedBackground;
 	QPixmap _pixmap;
 	QPixmap _pixmapForTiled;
 	bool _nightMode = false;
@@ -163,7 +168,7 @@ private:
 	QImage _themeImage;
 	bool _themeTile = false;
 
-	int32 _idForRevert = internal::kUninitializedBackground;
+	WallPaperId _idForRevert = internal::kUninitializedBackground;
 	QImage _imageForRevert;
 	bool _tileForRevert = false;