diff --git a/Telegram/Resources/langs/lang.strings b/Telegram/Resources/langs/lang.strings
index 8eb7c8e09..387db2670 100644
--- a/Telegram/Resources/langs/lang.strings
+++ b/Telegram/Resources/langs/lang.strings
@@ -1209,6 +1209,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 "lng_action_proximity_reached" = "{from} is now within {distance} from {user}";
 "lng_action_proximity_reached_you" = "{from} is now within {distance} from you";
 "lng_action_you_proximity_reached" = "You are now within {distance} from {user}";
+"lng_action_you_theme_changed" = "You changed chat theme to {emoji}";
+"lng_action_theme_changed" = "{from} changed chat theme to {emoji}";
+"lng_action_theme_changed_channel" = "Channel theme changed to {emoji}";
+"lng_action_you_theme_disabled" = "You disabled chat theme";
+"lng_action_theme_disabled" = "{from} disabled chat theme";
+"lng_action_theme_disabled_channel" = "Channel theme disabled";
 "lng_action_proximity_distance_m#one" = "{count} meter";
 "lng_action_proximity_distance_m#other" = "{count} metres";
 "lng_action_proximity_distance_km#one" = "{count} km";
diff --git a/Telegram/Resources/langs/stale.py b/Telegram/Resources/langs/stale.py
new file mode 100644
index 000000000..7b219f2c7
--- /dev/null
+++ b/Telegram/Resources/langs/stale.py
@@ -0,0 +1,17 @@
+import os, sys, requests, re
+
+os.chdir()
+
+keys = []
+with open('lang.strings') as f:
+    for line in f:
+        m = re.match(r'\"(lng_[a-z_]+)(\#[a-z]+)?\"', line)
+        if m:
+            keys.append(m.group(1))
+        elif not re.match(r'^\s*$', line):
+            print('Bad line: ' + line)
+            sys.exit(1)
+
+print('Keys: ' + str(len(keys)))
+
+sys.exit()
diff --git a/Telegram/SourceFiles/export/data/export_data_types.cpp b/Telegram/SourceFiles/export/data/export_data_types.cpp
index c331e4237..792a753a4 100644
--- a/Telegram/SourceFiles/export/data/export_data_types.cpp
+++ b/Telegram/SourceFiles/export/data/export_data_types.cpp
@@ -1124,7 +1124,9 @@ ServiceAction ParseServiceAction(
 			.date = data.vschedule_date().v,
 		};
 	}, [&](const MTPDmessageActionSetChatTheme &data) {
-		// #TODO themes
+		result.content = ActionSetChatTheme{
+			.emoji = qs(data.vemoticon()),
+		};
 	}, [](const MTPDmessageActionEmpty &data) {});
 	return result;
 }
diff --git a/Telegram/SourceFiles/export/data/export_data_types.h b/Telegram/SourceFiles/export/data/export_data_types.h
index 575393507..d1fd2f923 100644
--- a/Telegram/SourceFiles/export/data/export_data_types.h
+++ b/Telegram/SourceFiles/export/data/export_data_types.h
@@ -475,6 +475,10 @@ struct ActionGroupCallScheduled {
 	TimeId date = 0;
 };
 
+struct ActionSetChatTheme {
+	QString emoji;
+};
+
 struct ServiceAction {
 	std::variant<
 		v::null_t,
@@ -503,7 +507,8 @@ struct ServiceAction {
 		ActionGroupCall,
 		ActionInviteToGroupCall,
 		ActionSetMessagesTTL,
-		ActionGroupCallScheduled> content;
+		ActionGroupCallScheduled,
+		ActionSetChatTheme> content;
 };
 
 ServiceAction ParseServiceAction(
diff --git a/Telegram/SourceFiles/export/output/export_output_html.cpp b/Telegram/SourceFiles/export/output/export_output_html.cpp
index fc6638394..b14caa18c 100644
--- a/Telegram/SourceFiles/export/output/export_output_html.cpp
+++ b/Telegram/SourceFiles/export/output/export_output_html.cpp
@@ -1095,8 +1095,17 @@ auto HtmlWriter::Wrap::pushMessage(
 	}, [&](const ActionGroupCallScheduled &data) {
 		const auto dateText = FormatDateTime(data.date);
 		return isChannel
-			? "Voice chat scheduled for " + dateText
+			? ("Voice chat scheduled for " + dateText)
 			: (serviceFrom + " scheduled a voice chat for " + dateText);
+	}, [&](const ActionSetChatTheme &data) {
+		if (data.emoji.isEmpty()) {
+			return isChannel
+				? "Channel theme was disabled"
+				: (serviceFrom + " disabled chat theme");
+		}
+		return isChannel
+			? ("Channel theme was changed to " + data.emoji).toUtf8()
+			: (serviceFrom + " changed chat theme to " + data.emoji).toUtf8();
 	}, [](v::null_t) { return QByteArray(); });
 
 	if (!serviceText.isEmpty()) {
diff --git a/Telegram/SourceFiles/export/output/export_output_json.cpp b/Telegram/SourceFiles/export/output/export_output_json.cpp
index d9ac09164..4eb287498 100644
--- a/Telegram/SourceFiles/export/output/export_output_json.cpp
+++ b/Telegram/SourceFiles/export/output/export_output_json.cpp
@@ -517,6 +517,12 @@ QByteArray SerializeMessage(
 		pushActor();
 		pushAction("group_call_scheduled");
 		push("schedule_date", data.date);
+	}, [&](const ActionSetChatTheme &data) {
+		pushActor();
+		pushAction("edit_chat_theme");
+		if (!data.emoji.isEmpty()) {
+			push("emoticon", data.emoji.toUtf8());
+		}
 	}, [](v::null_t) {});
 
 	if (v::is_null(message.action.content)) {
diff --git a/Telegram/SourceFiles/history/history_service.cpp b/Telegram/SourceFiles/history/history_service.cpp
index aef8525a3..f74aa0b24 100644
--- a/Telegram/SourceFiles/history/history_service.cpp
+++ b/Telegram/SourceFiles/history/history_service.cpp
@@ -427,6 +427,31 @@ void HistoryService::setMessageByAction(const MTPmessageAction &action) {
 		return result;
 	};
 
+	auto prepareSetChatTheme = [this](const MTPDmessageActionSetChatTheme &action) {
+		auto result = PreparedText{};
+		const auto text = qs(action.vemoticon());
+		if (!text.isEmpty()) {
+			if (isPost()) {
+				result.text = tr::lng_action_theme_changed_channel(tr::now, lt_emoji, text);
+			} else if (_from->isSelf()) {
+				result.text = tr::lng_action_you_theme_changed(tr::now, lt_emoji, text);
+			} else {
+				result.links.push_back(fromLink());
+				result.text = tr::lng_action_theme_changed(tr::now, lt_from, fromLinkText(), lt_emoji, text);
+			}
+		} else {
+			if (isPost()) {
+				result.text = tr::lng_action_theme_disabled_channel(tr::now);
+			} else if (_from->isSelf()) {
+				result.text = tr::lng_action_you_theme_disabled(tr::now);
+			} else {
+				result.links.push_back(fromLink());
+				result.text = tr::lng_action_theme_disabled(tr::now, lt_from, fromLinkText());
+			}
+		}
+		return result;
+	};
+
 	const auto messageText = action.match([&](
 		const MTPDmessageActionChatAddUser &data) {
 		return prepareChatAddUserText(data);
@@ -485,7 +510,7 @@ void HistoryService::setMessageByAction(const MTPmessageAction &action) {
 	}, [&](const MTPDmessageActionGroupCallScheduled &data) {
 		return prepareCallScheduledText(data.vschedule_date().v);
 	}, [&](const MTPDmessageActionSetChatTheme &data) {
-		return PreparedText{ tr::lng_message_empty(tr::now) }; // #TODO themes
+		return prepareSetChatTheme(data);
 	}, [](const MTPDmessageActionEmpty &) {
 		return PreparedText{ tr::lng_message_empty(tr::now) };
 	});