diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index 2e7f67311d9e..a58162586d68 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -1625,6 +1625,10 @@
     "message": "Dark",
     "description": "Label text for dark theme"
   },
+  "themeSystem": {
+    "message": "System",
+    "description": "Label text for system theme"
+  },
   "noteToSelf": {
     "message": "Note to Self",
     "description": "Name for the conversation with your own phone number"
diff --git a/js/background.js b/js/background.js
index def21856baa8..78c29039efda 100644
--- a/js/background.js
+++ b/js/background.js
@@ -208,6 +208,7 @@
     switch (theme) {
       case 'dark':
       case 'light':
+      case 'system':
         return theme;
       case 'android-dark':
         return 'dark';
@@ -231,7 +232,11 @@
     window.Events = {
       getDeviceName: () => textsecure.storage.user.getDeviceName(),
 
-      getThemeSetting: () => storage.get('theme-setting', 'light'),
+      getThemeSetting: () =>
+        storage.get(
+          'theme-setting',
+          window.platform === 'darwin' ? 'system' : 'light'
+        ),
       setThemeSetting: value => {
         storage.put('theme-setting', value);
         onChangeTheme();
@@ -326,6 +331,19 @@
         `New version detected: ${currentVersion}; previous: ${lastVersion}`
       );
 
+      const themeSetting = window.Events.getThemeSetting();
+      const newThemeSetting = mapOldThemeToNew(themeSetting);
+
+      if (
+        window.isBeforeVersion(lastVersion, 'v1.25.0') &&
+        window.platform === 'darwin' &&
+        newThemeSetting === window.systemTheme
+      ) {
+        window.Events.setThemeSetting('system');
+      } else {
+        window.Events.setThemeSetting(newThemeSetting);
+      }
+
       if (window.isBeforeVersion(lastVersion, 'v1.25.0')) {
         // Stickers flags
         await Promise.all([
@@ -334,6 +352,7 @@
         ]);
       }
 
+      // This one should always be last - it could restart the app
       if (window.isBeforeVersion(lastVersion, 'v1.15.0-beta.5')) {
         await window.Signal.Logs.deleteAll();
         window.restart();
@@ -411,10 +430,6 @@
     };
     startSpellCheck();
 
-    const themeSetting = window.Events.getThemeSetting();
-    const newThemeSetting = mapOldThemeToNew(themeSetting);
-    window.Events.setThemeSetting(newThemeSetting);
-
     try {
       await Promise.all([
         ConversationController.load(),
diff --git a/js/permissions_popup_start.js b/js/permissions_popup_start.js
index f153a0bf96d3..668a934c964b 100644
--- a/js/permissions_popup_start.js
+++ b/js/permissions_popup_start.js
@@ -9,7 +9,23 @@ $(document).on('keyup', e => {
 });
 
 const $body = $(document.body);
-$body.addClass(`${window.theme}-theme`);
+
+async function applyTheme() {
+  'use strict';
+
+  const theme = await window.getThemeSetting();
+  $body.removeClass('light-theme');
+  $body.removeClass('dark-theme');
+  $body.addClass(`${theme === 'system' ? window.systemTheme : theme}-theme`);
+}
+
+applyTheme();
+
+window.subscribeToSystemThemeChange(() => {
+  'use strict';
+
+  applyTheme();
+});
 
 window.view = new Whisper.ConfirmationDialogView({
   message: i18n('audioPermissionNeeded'),
diff --git a/js/settings_start.js b/js/settings_start.js
index eeb85a66ac10..789a81fa8e75 100644
--- a/js/settings_start.js
+++ b/js/settings_start.js
@@ -9,7 +9,23 @@ $(document).on('keyup', e => {
 });
 
 const $body = $(document.body);
-$body.addClass(`${window.theme}-theme`);
+
+async function applyTheme() {
+  'use strict';
+
+  const theme = await window.getThemeSetting();
+  $body.removeClass('light-theme');
+  $body.removeClass('dark-theme');
+  $body.addClass(`${theme === 'system' ? window.systemTheme : theme}-theme`);
+}
+
+applyTheme();
+
+window.subscribeToSystemThemeChange(() => {
+  'use strict';
+
+  applyTheme();
+});
 
 // eslint-disable-next-line strict
 const getInitialData = async () => ({
diff --git a/js/views/app_view.js b/js/views/app_view.js
index 3fd906e98534..162f0b69f1a1 100644
--- a/js/views/app_view.js
+++ b/js/views/app_view.js
@@ -8,6 +8,14 @@
 
   window.Whisper = window.Whisper || {};
 
+  function resolveTheme() {
+    const theme = storage.get('theme-setting') || 'light';
+    if (window.platform === 'darwin' && theme === 'system') {
+      return window.systemTheme;
+    }
+    return theme;
+  }
+
   Whisper.AppView = Backbone.View.extend({
     initialize() {
       this.inboxView = null;
@@ -15,14 +23,18 @@
 
       this.applyTheme();
       this.applyHideMenu();
+
+      window.subscribeToSystemThemeChange(() => {
+        this.applyTheme();
+      });
     },
     events: {
       'click .openInstaller': 'openInstaller', // NetworkStatusView has this button
       openInbox: 'openInbox',
     },
     applyTheme() {
+      const theme = resolveTheme();
       const iOS = storage.get('userAgent') === 'OWI';
-      const theme = storage.get('theme-setting') || 'light';
       this.$el
         .removeClass('light-theme')
         .removeClass('dark-theme')
diff --git a/js/views/settings_view.js b/js/views/settings_view.js
index e17304a294d7..0b02a7fc835d 100644
--- a/js/views/settings_view.js
+++ b/js/views/settings_view.js
@@ -88,7 +88,9 @@
           $(document.body)
             .removeClass('dark-theme')
             .removeClass('light-theme')
-            .addClass(`${theme}-theme`);
+            .addClass(
+              `${theme === 'system' ? window.systemTheme : theme}-theme`
+            );
           window.setThemeSetting(theme);
         },
       });
@@ -143,8 +145,10 @@
         audioNotificationDescription: i18n('audioNotificationDescription'),
         isAudioNotificationSupported: Settings.isAudioNotificationSupported(),
         isHideMenuBarSupported: Settings.isHideMenuBarSupported(),
+        hasSystemTheme: window.platform === 'darwin',
         themeLight: i18n('themeLight'),
         themeDark: i18n('themeDark'),
+        themeSystem: i18n('themeSystem'),
         hideMenuBar: i18n('hideMenuBar'),
         clearDataHeader: i18n('clearDataHeader'),
         clearDataButton: i18n('clearDataButton'),
diff --git a/main.js b/main.js
index b1a06001e84c..ce4cd3829116 100644
--- a/main.js
+++ b/main.js
@@ -507,7 +507,6 @@ async function showSettingsWindow() {
     return;
   }
 
-  const theme = await pify(getDataFromMainWindow)('theme-setting');
   const size = mainWindow.getSize();
   const options = {
     width: Math.min(500, size[0]),
@@ -532,7 +531,7 @@ async function showSettingsWindow() {
 
   captureClicks(settingsWindow);
 
-  settingsWindow.loadURL(prepareURL([__dirname, 'settings.html'], { theme }));
+  settingsWindow.loadURL(prepareURL([__dirname, 'settings.html']));
 
   settingsWindow.on('closed', () => {
     removeDarkOverlay();
diff --git a/package.json b/package.json
index f825c1829539..799b3beb23b3 100644
--- a/package.json
+++ b/package.json
@@ -181,6 +181,7 @@
     "mac": {
       "artifactName": "${name}-mac-${version}.${ext}",
       "category": "public.app-category.social-networking",
+      "darkModeSupport": true,
       "icon": "build/icons/mac/icon.icns",
       "publish": [
         {
diff --git a/permissions_popup_preload.js b/permissions_popup_preload.js
index 621a5fc7ce2b..bf8efc299bde 100644
--- a/permissions_popup_preload.js
+++ b/permissions_popup_preload.js
@@ -1,9 +1,11 @@
 /* global window */
 
-const { ipcRenderer } = require('electron');
+const { ipcRenderer, remote } = require('electron');
 const url = require('url');
 const i18n = require('./js/modules/i18n');
 
+const { systemPreferences } = remote.require('electron');
+
 const config = url.parse(window.location.toString(), true).query;
 const { locale } = config;
 const localeMessages = ipcRenderer.sendSync('locale-data');
@@ -12,6 +14,25 @@ window.getVersion = () => config.version;
 window.theme = config.theme;
 window.i18n = i18n.setup(locale, localeMessages);
 
+function setSystemTheme() {
+  window.systemTheme = systemPreferences.isDarkMode() ? 'dark' : 'light';
+}
+
+setSystemTheme();
+
+window.subscribeToSystemThemeChange = fn => {
+  if (!systemPreferences.subscribeNotification) {
+    return;
+  }
+  systemPreferences.subscribeNotification(
+    'AppleInterfaceThemeChangedNotification',
+    () => {
+      setSystemTheme();
+      fn();
+    }
+  );
+};
+
 require('./js/logging');
 
 window.closePermissionsPopup = () =>
@@ -19,6 +40,8 @@ window.closePermissionsPopup = () =>
 
 window.getMediaPermissions = makeGetter('media-permissions');
 window.setMediaPermissions = makeSetter('media-permissions');
+window.getThemeSetting = makeGetter('theme-setting');
+window.setThemeSetting = makeSetter('theme-setting');
 
 function makeGetter(name) {
   return () =>
diff --git a/preload.js b/preload.js
index 48a516565808..69a34b2d04a8 100644
--- a/preload.js
+++ b/preload.js
@@ -7,6 +7,7 @@ const semver = require('semver');
 const { deferredToPromise } = require('./js/modules/deferred_to_promise');
 
 const { app } = electron.remote;
+const { systemPreferences } = electron.remote.require('electron');
 
 window.PROTO_ROOT = 'protos';
 const config = require('url').parse(window.location.toString(), true).query;
@@ -31,6 +32,25 @@ window.getHostName = () => config.hostname;
 window.getServerTrustRoot = () => config.serverTrustRoot;
 window.isBehindProxy = () => Boolean(config.proxyUrl);
 
+function setSystemTheme() {
+  window.systemTheme = systemPreferences.isDarkMode() ? 'dark' : 'light';
+}
+
+setSystemTheme();
+
+window.subscribeToSystemThemeChange = fn => {
+  if (!systemPreferences.subscribeNotification) {
+    return;
+  }
+  systemPreferences.subscribeNotification(
+    'AppleInterfaceThemeChangedNotification',
+    () => {
+      setSystemTheme();
+      fn();
+    }
+  );
+};
+
 window.isBeforeVersion = (toCheck, baseVersion) => {
   try {
     return semver.lt(toCheck, baseVersion);
diff --git a/settings.html b/settings.html
index bf14f2444012..184b117a211c 100644
--- a/settings.html
+++ b/settings.html
@@ -44,6 +44,12 @@
     <hr>
     <div class='theme-settings'>
       <h3>{{ theme }}</h3>
+      {{#hasSystemTheme}}
+        <div>
+          <input type='radio' name='theme' id='theme-setting-system' value='system'>
+          <label for='theme-setting-system'>{{ themeSystem }}</label>
+        </div>
+      {{/hasSystemTheme}}
       <div>
         <input type='radio' name='theme' id='theme-setting-light' value='light'>
         <label for='theme-setting-light'>{{ themeLight }}</label>
diff --git a/settings_preload.js b/settings_preload.js
index 858a88c29be7..9018fa1ca683 100644
--- a/settings_preload.js
+++ b/settings_preload.js
@@ -1,6 +1,7 @@
 /* global window */
 
-const { ipcRenderer } = require('electron');
+const { ipcRenderer, remote } = require('electron');
+
 const url = require('url');
 const i18n = require('./js/modules/i18n');
 
@@ -8,9 +9,31 @@ const config = url.parse(window.location.toString(), true).query;
 const { locale } = config;
 const localeMessages = ipcRenderer.sendSync('locale-data');
 
+const { systemPreferences } = remote.require('electron');
+
+window.platform = process.platform;
 window.theme = config.theme;
 window.i18n = i18n.setup(locale, localeMessages);
 
+function setSystemTheme() {
+  window.systemTheme = systemPreferences.isDarkMode() ? 'dark' : 'light';
+}
+
+setSystemTheme();
+
+window.subscribeToSystemThemeChange = fn => {
+  if (!systemPreferences.subscribeNotification) {
+    return;
+  }
+  systemPreferences.subscribeNotification(
+    'AppleInterfaceThemeChangedNotification',
+    () => {
+      setSystemTheme();
+      fn();
+    }
+  );
+};
+
 window.getEnvironment = () => config.environment;
 window.getVersion = () => config.version;
 window.getAppInstance = () => config.appInstance;
diff --git a/ts/util/lint/exceptions.json b/ts/util/lint/exceptions.json
index 2e7cfe0c3e9a..5a31a3798d83 100644
--- a/ts/util/lint/exceptions.json
+++ b/ts/util/lint/exceptions.json
@@ -257,7 +257,7 @@
     "rule": "jQuery-appendTo(",
     "path": "js/permissions_popup_start.js",
     "line": "window.view.$el.appendTo($body);",
-    "lineNumber": 26,
+    "lineNumber": 42,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T18:13:29.628Z",
     "reasonDetail": "Interacting with already-existing DOM nodes"
@@ -284,7 +284,7 @@
     "rule": "jQuery-appendTo(",
     "path": "js/settings_start.js",
     "line": "    window.view.$el.appendTo($body);",
-    "lineNumber": 41,
+    "lineNumber": 57,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T18:13:29.628Z",
     "reasonDetail": "Interacting with already-existing DOM nodes"
@@ -317,7 +317,7 @@
     "rule": "DOM-innerHTML",
     "path": "js/views/app_view.js",
     "line": "      this.el.innerHTML = '';",
-    "lineNumber": 43,
+    "lineNumber": 55,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-15T00:38:04.183Z",
     "reasonDetail": "Hard-coded string"
@@ -326,7 +326,7 @@
     "rule": "jQuery-append(",
     "path": "js/views/app_view.js",
     "line": "      this.el.append(view.el);",
-    "lineNumber": 44,
+    "lineNumber": 56,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T18:13:29.628Z",
     "reasonDetail": "Interacting with already-existing DOM nodes"
@@ -335,7 +335,7 @@
     "rule": "jQuery-appendTo(",
     "path": "js/views/app_view.js",
     "line": "      this.debugLogView.$el.appendTo(this.el);",
-    "lineNumber": 50,
+    "lineNumber": 62,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T18:13:29.628Z",
     "reasonDetail": "Interacting with already-existing DOM nodes"
@@ -1008,7 +1008,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "          el: this.$('.audio-notification-setting'),",
-    "lineNumber": 97,
+    "lineNumber": 99,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1017,7 +1017,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "        el: this.$('.spell-check-setting'),",
-    "lineNumber": 104,
+    "lineNumber": 106,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1026,7 +1026,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "          el: this.$('.menu-bar-setting'),",
-    "lineNumber": 111,
+    "lineNumber": 113,
     "reasonCategory": "usageTrusted",
     "updated": "2019-04-08T18:24:35.255Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1035,7 +1035,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "        el: this.$('.media-permissions'),",
-    "lineNumber": 118,
+    "lineNumber": 120,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1044,7 +1044,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "        this.$('.sync-setting').append(syncView.el);",
-    "lineNumber": 124,
+    "lineNumber": 126,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1053,7 +1053,7 @@
     "rule": "jQuery-append(",
     "path": "js/views/settings_view.js",
     "line": "        this.$('.sync-setting').append(syncView.el);",
-    "lineNumber": 124,
+    "lineNumber": 126,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T18:13:29.628Z",
     "reasonDetail": "Interacting with already-existing DOM nodes"
@@ -1062,25 +1062,25 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "      this.$('.sync').text(i18n('syncNow'));",
-    "lineNumber": 179,
-    "reasonCategory": "usageTrusted",
-    "updated": "2018-09-19T21:59:32.770Z",
-    "reasonDetail": "Protected from arbitrary input"
-  },
-  {
-    "rule": "jQuery-$(",
-    "path": "js/views/settings_view.js",
-    "line": "      this.$('.sync').attr('disabled', 'disabled');",
     "lineNumber": 183,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
   },
+  {
+    "rule": "jQuery-$(",
+    "path": "js/views/settings_view.js",
+    "line": "      this.$('.sync').attr('disabled', 'disabled');",
+    "lineNumber": 187,
+    "reasonCategory": "usageTrusted",
+    "updated": "2018-09-19T21:59:32.770Z",
+    "reasonDetail": "Protected from arbitrary input"
+  },
   {
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "      this.$('.synced_at').hide();",
-    "lineNumber": 195,
+    "lineNumber": 199,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"
@@ -1089,7 +1089,7 @@
     "rule": "jQuery-$(",
     "path": "js/views/settings_view.js",
     "line": "      this.$('.sync_failed').hide();",
-    "lineNumber": 200,
+    "lineNumber": 204,
     "reasonCategory": "usageTrusted",
     "updated": "2018-09-19T21:59:32.770Z",
     "reasonDetail": "Protected from arbitrary input"