diff --git a/README.md b/README.md
index 5e2f450..8575c73 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,7 @@ The external links module is a task and ModelAdmin to track and to report on bro
  3. Run the following task *http://path.to.silverstripe/dev/tasks/CheckExternalLinks* to check for
     broken external links
 
-## Report ##
+## Report
 
 A new report is added called 'External Broken links report'. When viewing this report, a user may press
 the "Create new report" button which will trigger an ajax request to initiate a report run.
@@ -56,24 +56,30 @@ with the status. The user may leave this page and return to it later to view the
 
 Any subsequent report may not be generated until a prior report has completed.
 
-## Dev task ##
+## Dev task
 
 Run the following task *http://path.to.silverstripe/dev/tasks/CheckExternalLinks* to check your site for external
 broken links.
 
-## Queued job ##
+## Queued job
 
 If you have the queuedjobs module installed you can set the task to be run every so often.
 
-## Whitelisting codes ##
+## Whitelisting codes
 
-If you want to ignore or whitelist certain http codes this can be setup via IgnoreCodes in the config.yml
-file in `mysite/_config`
+If you want to ignore or whitelist certain HTTP codes this can be setup via `ignore_codes` in the config.yml
+file in `mysite/_config`:
 
 ```yml
-    SilverStripe\ExternalLinks\Tasks\CheckExternalLinksTask:
-      IgnoreCodes:
-        - 401
-        - 403
-        - 501
+SilverStripe\ExternalLinks\Tasks\CheckExternalLinksTask:
+  ignore_codes:
+    - 401
+    - 403
+    - 501
 ```
+
+## Upgrading from 1.x to 2.x
+
+When upgrading from 1.x to 2.x (SilverStripe 3.x to 4.x) you will need to be aware of the following API changes:
+
+ * Configuration property `CheckExternalLinksTask.IgnoreCodes` renamed to `CheckExternalLinksTask.ignore_codes`
diff --git a/src/Model/BrokenExternalLink.php b/src/Model/BrokenExternalLink.php
index 0aa2037..366057a 100644
--- a/src/Model/BrokenExternalLink.php
+++ b/src/Model/BrokenExternalLink.php
@@ -2,13 +2,12 @@
 
 namespace SilverStripe\ExternalLinks\Model;
 
+use SilverStripe\Control\HTTPResponse;
 use SilverStripe\ExternalLinks\Model\BrokenExternalPageTrack;
 use SilverStripe\ExternalLinks\Model\BrokenExternalPageTrackStatus;
-use SilverStripe\Security\Member;
-use SilverStripe\Security\Permission;
-use SilverStripe\Core\Config\Config;
-use SilverStripe\Control\HTTPResponse;
 use SilverStripe\ORM\DataObject;
+use SilverStripe\Security\Permission;
+use SilverStripe\Security\Security;
 
 /**
  * Represents a single link checked for a single run that is broken
@@ -56,7 +55,7 @@ class BrokenExternalLink extends DataObject
 
     public function canView($member = false)
     {
-        $member = $member ? $member : Member::currentUser();
+        $member = $member ? $member : Security::getCurrentUser();
         $codes = array('content-authors', 'administrators');
         return Permission::checkMember($member, $codes);
     }
diff --git a/src/Tasks/CheckExternalLinksTask.php b/src/Tasks/CheckExternalLinksTask.php
index 84a8551..d83d5fe 100644
--- a/src/Tasks/CheckExternalLinksTask.php
+++ b/src/Tasks/CheckExternalLinksTask.php
@@ -2,26 +2,36 @@
 
 namespace SilverStripe\ExternalLinks\Tasks;
 
+use DOMNode;
+use SilverStripe\CMS\Model\SiteTree;
+use SilverStripe\Core\Config\Config;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Dev\BuildTask;
+use SilverStripe\Dev\Debug;
 use SilverStripe\ExternalLinks\Model\BrokenExternalLink;
 use SilverStripe\ExternalLinks\Model\BrokenExternalPageTrack;
 use SilverStripe\ExternalLinks\Model\BrokenExternalPageTrackStatus;
-use SilverStripe\Dev\BuildTask;
-use SilverStripe\Core\Config\Config;
+use SilverStripe\ExternalLinks\Tasks\LinkChecker;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DB;
-use SilverStripe\Dev\Debug;
-use DOMNode;
-use SilverStripe\Core\Injector\Injector;
-use SilverStripe\ExternalLinks\Tasks\LinkChecker;
-use SilverStripe\CMS\Model\SiteTree;
 
 class CheckExternalLinksTask extends BuildTask
 {
-
     private static $dependencies = [
         'LinkChecker' => '%$' . LinkChecker::class
     ];
 
+    private static $segment = 'CheckExternalLinksTask';
+
+    /**
+     * Define a list of HTTP response codes that should not be treated as "broken", where they usually
+     * might be.
+     *
+     * @config
+     * @var array
+     */
+    private static $ignore_codes = [];
+
     /**
      * @var bool
      */
@@ -135,7 +145,7 @@ class CheckExternalLinksTask extends BuildTask
         }
 
         // do we have any whitelisted codes
-        $ignoreCodes = $this->config()->get('IgnoreCodes');
+        $ignoreCodes = $this->config()->get('ignore_codes');
         if (is_array($ignoreCodes) && in_array($httpCode, $ignoreCodes)) {
             return false;
         }