diff --git a/omega-target-chromium-extension/background.coffee b/omega-target-chromium-extension/background.coffee
index 50fb17c..ca93899 100644
--- a/omega-target-chromium-extension/background.coffee
+++ b/omega-target-chromium-extension/background.coffee
@@ -147,11 +147,11 @@ actionForUrl = (url) ->
     }
 
 
-storage = new OmegaTargetCurrent.Storage(chrome.storage.local, 'local')
+storage = new OmegaTargetCurrent.Storage('local')
 state = new OmegaTargetCurrent.BrowserStorage(localStorage, 'omega.local.')
 
-if chrome.storage.sync
-  syncStorage = new OmegaTargetCurrent.Storage(chrome.storage.sync, 'sync')
+if chrome?.storage?.sync or browser?.storage?.sync
+  syncStorage = new OmegaTargetCurrent.Storage('sync')
   sync = new OmegaTargetCurrent.OptionsSync(syncStorage)
   if localStorage['omega.local.syncOptions'] != '"sync"'
     sync.enabled = false
diff --git a/omega-target-chromium-extension/src/chrome_port.coffee b/omega-target-chromium-extension/src/chrome_port.coffee
index 0cddb01..e007b11 100644
--- a/omega-target-chromium-extension/src/chrome_port.coffee
+++ b/omega-target-chromium-extension/src/chrome_port.coffee
@@ -34,8 +34,10 @@ class TrackedEvent
   constructor: (@event) ->
     @callbacks = []
     mes = ['hasListener', 'hasListeners', 'addRules', 'getRules', 'removeRules']
-    for method in mes
-      this[method] = @event[method].bind(@event)
+    for methodName in mes
+      method = @event[methodName]
+      if method?
+        this[methodName] = method.bind(@event)
 
   addListener: (callback) ->
     @event.addListener(callback)
@@ -69,7 +71,7 @@ class TrackedEvent
   ###
   dispose: ->
     @removeAllListeners()
-    if @event.hasListeners()
+    if @event.hasListeners?()
       throw new Error("Underlying Event still has listeners!")
     @event = null
     @callbacks = null
diff --git a/omega-target-chromium-extension/src/external_api.coffee b/omega-target-chromium-extension/src/external_api.coffee
index a080718..6768809 100644
--- a/omega-target-chromium-extension/src/external_api.coffee
+++ b/omega-target-chromium-extension/src/external_api.coffee
@@ -10,6 +10,7 @@ module.exports = class ExternalApi
     'padekgcemlokbadohgkifijomclgjgif': 32
   disabled: false
   listen: ->
+    return unless chrome.runtime.onConnectExternal
     chrome.runtime.onConnectExternal.addListener (rawPort) =>
       port = new ChromePort(rawPort)
       port.onMessage.addListener (msg) => @onMessage(msg, port)
diff --git a/omega-target-chromium-extension/src/options.coffee b/omega-target-chromium-extension/src/options.coffee
index ecf9185..8f5db9f 100644
--- a/omega-target-chromium-extension/src/options.coffee
+++ b/omega-target-chromium-extension/src/options.coffee
@@ -3,7 +3,14 @@ OmegaPac = OmegaTarget.OmegaPac
 Promise = OmegaTarget.Promise
 querystring = require('querystring')
 chromeApiPromisifyAll = require('./chrome_api')
-proxySettings = chromeApiPromisifyAll(chrome.proxy.settings)
+if chrome?.proxy?.settings
+  proxySettings = chromeApiPromisifyAll(chrome.proxy.settings)
+else
+  proxySettings =
+    setAsync: -> Promise.resolve()
+    clearAsync: -> Promise.resolve()
+    get: -> null
+    onChange: addListener: -> null
 parseExternalProfile = require('./parse_external_profile')
 ProxyAuth = require('./proxy_auth')
 WebRequestMonitor = require('./web_request_monitor')
@@ -118,14 +125,14 @@ class ChromeOptions extends OmegaTarget.Options
       @_proxyChangeListener = (details) =>
         for watcher in @_proxyChangeWatchers
           watcher(details)
-      chrome.proxy.settings.onChange.addListener @_proxyChangeListener
+      proxySettings.onChange.addListener @_proxyChangeListener
     @_proxyChangeWatchers.push(callback)
   applyProfileProxy: (profile, meta) ->
     meta ?= profile
     if profile.profileType == 'SystemProfile'
       # Clear proxy settings, returning proxy control to Chromium.
       return proxySettings.clearAsync({}).then =>
-        chrome.proxy.settings.get {}, @_proxyChangeListener
+        proxySettings.get {}, @_proxyChangeListener
         return
     config = {}
     if profile.profileType == 'DirectProfile'
@@ -161,7 +168,7 @@ class ChromeOptions extends OmegaTarget.Options
       @_proxyAuth.setProxies(@_watchingProfiles)
       proxySettings.setAsync({value: config})
     ).then =>
-      chrome.proxy.settings.get {}, @_proxyChangeListener
+      proxySettings.get {}, @_proxyChangeListener
       return
 
   _quickSwitchInit: false
diff --git a/omega-target-chromium-extension/src/proxy_auth.coffee b/omega-target-chromium-extension/src/proxy_auth.coffee
index e11d17c..50aa764 100644
--- a/omega-target-chromium-extension/src/proxy_auth.coffee
+++ b/omega-target-chromium-extension/src/proxy_auth.coffee
@@ -13,6 +13,9 @@ module.exports = class ProxyAuth
     if not chrome.webRequest
       @options.log.error('Proxy auth disabled! No webRequest permission.')
       return
+    if not chrome.webRequest.onAuthRequired
+      @options.log.error('Proxy auth disabled! onAuthRequired not available.')
+      return
     chrome.webRequest.onAuthRequired.addListener(
       @authHandler.bind(this)
       {urls: ['<all_urls>']}
diff --git a/omega-target-chromium-extension/src/storage.coffee b/omega-target-chromium-extension/src/storage.coffee
index c7069e0..0838491 100644
--- a/omega-target-chromium-extension/src/storage.coffee
+++ b/omega-target-chromium-extension/src/storage.coffee
@@ -28,27 +28,40 @@ class ChromeStorage extends OmegaTarget.Storage
         # This could happen if the storage area is not available. For example,
         # some Chromium-based browsers disable access to the sync storage.
         err = new OmegaTarget.Storage.StorageUnavailableError()
+      else if err.message.indexOf(
+        'Please set webextensions.storage.sync.enabled to true') >= 0
+        # This happens when sync storage is disabled in flags.
+        err = new OmegaTarget.Storage.StorageUnavailableError()
 
     return Promise.reject(err)
 
-  constructor: (storage, @areaName) ->
-    @storage = chromeApiPromisifyAll(storage)
+  constructor: (@areaName) ->
+    if browser?.storage?[@areaName]
+      @storage = browser.storage[@areaName]
+    else
+      wrapper = chromeApiPromisifyAll(chrome.storage[@areaName])
+      @storage =
+        get: wrapper.getAsync.bind(wrapper),
+        set: wrapper.setAsync.bind(wrapper),
+        remove: wrapper.removeAsync.bind(wrapper),
+        clear: wrapper.clearAsync.bind(wrapper),
 
   get: (keys) ->
     keys ?= null
-    @storage.getAsync(keys).catch(ChromeStorage.parseStorageErrors)
+    Promise.resolve(@storage.get(keys)).catch(ChromeStorage.parseStorageErrors)
 
   set: (items) ->
     if Object.keys(items).length == 0
       return Promise.resolve({})
-    @storage.setAsync(items).catch(ChromeStorage.parseStorageErrors)
+    Promise.resolve(@storage.set(items)).catch(ChromeStorage.parseStorageErrors)
 
   remove: (keys) ->
     if not keys?
-      return @storage.clearAsync()
+      return Promise.resolve(@storage.clear())
     if Array.isArray(keys) and keys.length == 0
       return Promise.resolve({})
-    @storage.removeAsync(keys).catch(ChromeStorage.parseStorageErrors)
+    Promise.resolve(@storage.remove(keys))
+      .catch(ChromeStorage.parseStorageErrors)
 
   watch: (keys, callback) ->
     ChromeStorage.watchers[@areaName] ?= {}