diff --git a/composer.json b/composer.json
index 9e6c863..34985d4 100644
--- a/composer.json
+++ b/composer.json
@@ -5,16 +5,18 @@
     "license": "MIT",
 
     "require": {
-        "silverstripe/framework": "^4",
-        "silverstripe/admin": "^1.0",
-        "symbiote/silverstripe-gridfieldextensions": "^3",
+        "php": "^8.1",
+        "silverstripe/framework": "^5",
+        "silverstripe/admin": "^2",
+        "symbiote/silverstripe-gridfieldextensions": "^4",
         "s1lentium/iptools": "^1.1",
-        "silverstripe/auditor": "^2"
+        "silverstripe/auditor": "^3",
+        "silverstripe/errorpage": "^2"
     },
 
     "require-dev": {
-        "phpunit/phpunit": "^5.7",
-        "squizlabs/php_codesniffer": "^3.0"
+        "phpunit/phpunit": "^9.5",
+        "squizlabs/php_codesniffer": "^3"
     },
 
     "autoload": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index d388c89..148898a 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,14 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/silverstripe/framework/tests/bootstrap.php" colors="true">
-    <testsuite name="madmatt/silverstripe-iplists">
-        <directory>tests/</directory>
-    </testsuite>
-    <filter>
-        <whitelist addUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">src/</directory>
-            <exclude>
-                <directory suffix=".php">tests/</directory>
-            </exclude>
-        </whitelist>
-    </filter>
-</phpunit>
\ No newline at end of file
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="vendor/silverstripe/framework/tests/bootstrap.php" colors="true" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage includeUncoveredFiles="true">
+    <include>
+      <directory suffix=".php">src/</directory>
+    </include>
+    <exclude>
+      <directory suffix=".php">tests/</directory>
+    </exclude>
+  </coverage>
+  <testsuite name="madmatt/silverstripe-iplists">
+    <directory>tests/</directory>
+  </testsuite>
+</phpunit>
diff --git a/src/Admin/IPListAdmin.php b/src/Admin/IPListAdmin.php
index 60a7517..26fed5a 100644
--- a/src/Admin/IPListAdmin.php
+++ b/src/Admin/IPListAdmin.php
@@ -9,27 +9,28 @@
 
 class IPListAdmin extends ModelAdmin
 {
-    private static $menu_title = 'IP Lists';
+    private static string $menu_title = 'IP Lists';
 
-    private static $url_segment = 'ip-lists';
+    private static string $url_segment = 'ip-lists';
 
-    private static $menu_icon_class = 'font-icon-lock';
+    private static string $menu_icon_class = 'font-icon-lock';
 
-    private static $managed_models = [
+    private static array $managed_models = [
         IPList::class,
         IP::class
     ];
 
+    /**
+     * @inheritDoc
+     */
     public function getEditForm($id = null, $fields = null)
     {
         $form = parent::getEditForm($id, $fields);
 
-        if ($this->modelClass == IP::class) {
+        if ($this->modelClass === IP::class) {
             $msg = '<div class="alert alert-warning"><strong>Caution:</strong> Removing IPs from this list will remove'
                 . ' them from all IP lists and the database.</div>';
             $form->Fields()->insertBefore($this->sanitiseClassName(IP::class), LiteralField::create('IPHelper', $msg));
-
-
         }
 
         return $form;
diff --git a/src/Middleware/IPListMiddleware.php b/src/Middleware/IPListMiddleware.php
index 1010105..5cd5381 100644
--- a/src/Middleware/IPListMiddleware.php
+++ b/src/Middleware/IPListMiddleware.php
@@ -5,26 +5,26 @@
 use Madmatt\IPLists\Service\IPListService;
 use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTPRequest;
-use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Control\Middleware\HTTPMiddleware;
 use SilverStripe\Core\Config\Configurable;
 use SilverStripe\Core\Injector\Injectable;
 
 class IPListMiddleware implements HTTPMiddleware
 {
-    use Configurable, Injectable;
+    use Configurable;
+    use Injectable;
 
     /**
      * @var bool Defaults to true, set this to false via YML config to globally disable the middleware
      * @config
      */
-    private static $enabled = true;
+    private static bool $enabled = true;
 
     /**
      * @var bool Defaults to true, set this to false via YML config to disable the middleware on development enviroments
      * @config
      */
-    private static $enabled_on_dev = true;
+    private static bool $enabled_on_dev = true;
 
     /**
      * @var bool Defaults to false, set this to true via YML config to enable the middleware on the command-line
@@ -32,14 +32,14 @@ class IPListMiddleware implements HTTPMiddleware
      * extends *HTTPMiddleware*, so you'd only expect it to apply to HTTP requests but it also applies to cli).
      * @config
      */
-    private static $enabled_on_cli = false;
+    private static bool $enabled_on_cli = false;
 
     /**
      * @var IPListService
      */
     public $service;
 
-    private static $dependencies = [
+    private static array $dependencies = [
         'service' => '%$' . IPListService::class
     ];
 
diff --git a/src/Model/IP.php b/src/Model/IP.php
index 013c422..8c51c51 100644
--- a/src/Model/IP.php
+++ b/src/Model/IP.php
@@ -3,11 +3,9 @@
 namespace Madmatt\IPLists\Model;
 
 use Exception;
-use IPTools\Network;
 use IPTools\Range;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\FieldType\DBField;
-use SilverStripe\ORM\FieldType\DBVarchar;
 use SilverStripe\ORM\ManyManyList;
 
 /**
@@ -30,9 +28,9 @@
  */
 class IP extends DataObject
 {
-    private static $singular_name = 'IP';
+    private static string $singular_name = 'IP';
 
-    private static $table_name = 'IPLists_IP';
+    private static string $table_name = 'IPLists_IP';
 
     private static $db = [
         'AddressType' => 'Enum(array("' . self::TYPE_IP . '","' . self::TYPE_CIDR . '"), "' . self::TYPE_IP . '")',
@@ -40,19 +38,19 @@ class IP extends DataObject
         'Title' => 'Varchar(200)',
     ];
 
-    private static $belongs_many_many = [
+    private static array $belongs_many_many = [
         'Lists' => IPList::class
     ];
 
-    private static $summary_fields = [
+    private static array $summary_fields = [
         'Title' => 'Title',
         'IP' => 'IP',
         'AddressType' => 'AddressType',
         'UsedInLists' => 'Used in...'
     ];
 
-    const TYPE_IP = 'IP';
-    const TYPE_CIDR = 'CIDR';
+    public const TYPE_IP = 'IP';
+    public const TYPE_CIDR = 'CIDR';
 
     public function getCMSFields()
     {
diff --git a/src/Model/IPList.php b/src/Model/IPList.php
index 10437f0..ad7ed50 100644
--- a/src/Model/IPList.php
+++ b/src/Model/IPList.php
@@ -10,18 +10,11 @@
 use SilverStripe\Forms\GridField\GridField;
 use SilverStripe\Forms\GridField\GridField_ActionMenu;
 use SilverStripe\Forms\GridField\GridFieldAddExistingAutocompleter;
-use SilverStripe\Forms\GridField\GridFieldAddNewButton;
 use SilverStripe\Forms\GridField\GridFieldButtonRow;
 use SilverStripe\Forms\GridField\GridFieldConfig;
-use SilverStripe\Forms\GridField\GridFieldConfig_RelationEditor;
-use SilverStripe\Forms\GridField\GridFieldDataColumns;
 use SilverStripe\Forms\GridField\GridFieldDeleteAction;
 use SilverStripe\Forms\GridField\GridFieldDetailForm;
 use SilverStripe\Forms\GridField\GridFieldEditButton;
-use SilverStripe\Forms\GridField\GridFieldFilterHeader;
-use SilverStripe\Forms\GridField\GridFieldPageCount;
-use SilverStripe\Forms\GridField\GridFieldPaginator;
-use SilverStripe\Forms\GridField\GridFieldSortableHeader;
 use SilverStripe\Forms\GridField\GridFieldToolbarHeader;
 use SilverStripe\Forms\LiteralField;
 use SilverStripe\Forms\NumericField;
@@ -30,11 +23,8 @@
 use SilverStripe\Forms\TextField;
 use SilverStripe\Forms\ToggleCompositeField;
 use SilverStripe\ORM\DataObject;
-use SilverStripe\ORM\FieldType\DBField;
-use SilverStripe\ORM\FieldType\DBHTMLVarchar;
 use Symbiote\GridFieldExtensions\GridFieldAddNewInlineButton;
 use Symbiote\GridFieldExtensions\GridFieldEditableColumns;
-use Symbiote\GridFieldExtensions\GridFieldOrderableRows;
 use Symbiote\GridFieldExtensions\GridFieldTitleHeader;
 
 /**
@@ -54,13 +44,13 @@
  */
 class IPList extends DataObject
 {
-    private static $singular_name = 'IP list';
+    private static string $singular_name = 'IP list';
 
-    private static $table_name = 'IPLists_IPList';
+    private static string $table_name = 'IPLists_IPList';
 
-    private static $default_sort = 'Priority DESC, ID ASC';
+    private static string $default_sort = 'Priority DESC, ID ASC';
 
-    private static $db = [
+    private static array $db = [
         'Title' => 'Varchar(200)',
         'Description' => 'Text',
         'Enabled' => 'Boolean',
@@ -70,24 +60,24 @@ class IPList extends DataObject
         'ProtectedRoutes' => 'Text',
     ];
 
-    private static $many_many = [
+    private static array $many_many = [
         'IPs' => IP::class
     ];
 
-    private static $many_many_extraFields = [
+    private static array $many_many_extraFields = [
         'IPs' => [
             'Sort' => 'Int'
         ]
     ];
 
-    private static $defaults = [
+    private static array $defaults = [
         'Enabled' => true,
         'Priority' => 100,
         'ListType' => self::LIST_TYPE_ALLOW,
         'DenyMethod' => self::DENY_METHOD_404,
     ];
 
-    private static $summary_fields = [
+    private static array $summary_fields = [
         'Title' => 'Title',
         'Description' => 'Description',
         'Enabled.Nice' => 'Is Enabled?',
@@ -95,11 +85,11 @@ class IPList extends DataObject
         'IPs.Count' => 'Number of IPs'
     ];
 
-    const LIST_TYPE_DENY = 'Deny';
-    const LIST_TYPE_ALLOW = 'Allow';
+    public const LIST_TYPE_DENY = 'Deny';
+    public const LIST_TYPE_ALLOW = 'Allow';
 
-    const DENY_METHOD_404 = 404;
-    const DENY_METHOD_400 = 400;
+    public const DENY_METHOD_404 = 404;
+    public const DENY_METHOD_400 = 400;
 
     public function getCMSFields()
     {
diff --git a/src/Service/IPListService.php b/src/Service/IPListService.php
index 2c9db93..cbc8637 100644
--- a/src/Service/IPListService.php
+++ b/src/Service/IPListService.php
@@ -7,8 +7,8 @@
 use LogicException;
 use Madmatt\IPLists\Model\IP;
 use Madmatt\IPLists\Model\IPList;
+use Monolog\Level;
 use Monolog\Logger;
-use PageController;
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\Session;
@@ -22,7 +22,7 @@ class IPListService
      */
     public $auditLogger;
 
-    private static $dependencies = [
+    private static array $dependencies = [
         'auditLogger' => '%$AuditLogger'
     ];
 
@@ -39,10 +39,7 @@ class IPListService
     public const IP_ACCESS_DENIED = 0;
     public const IP_ACCESS_AMBIVALENT = -1;
 
-    /**
-     * @var array
-     */
-    private $validLists = [];
+    private array $validLists = [];
 
     /**
      * Check all {@link IPList} objects to find any that match the given URL route. If one is found, confirm whether the
@@ -214,13 +211,13 @@ protected function log(int $allowOrDeny = -1, array $context = [])
         switch ($allowOrDeny) {
             case self::IP_ACCESS_ALLOWED:
                 $message = $successLogMsg;
-                $logLevel = Logger::DEBUG;
+                $logLevel = Level::Debug;
                 $msgType = 'success';
                 break;
 
             case self::IP_ACCESS_DENIED:
                 $message = $failureLogMsg;
-                $logLevel = Logger::WARNING;
+                $logLevel = Level::Warning;
                 $msgType = 'failure';
                 break;
 
diff --git a/tests/Model/IPListTest.php b/tests/Model/IPListTest.php
index 977a4f4..222478f 100644
--- a/tests/Model/IPListTest.php
+++ b/tests/Model/IPListTest.php
@@ -4,23 +4,28 @@
 
 use Madmatt\IPLists\Model\IPList;
 use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Forms\LiteralField;
 
 class IPListTest extends SapphireTest
 {
     protected $usesDatabase = true;
 
-    public function testGetCMSFieldsIPHelpMessage()
+    public function testGetCMSFieldsIPHelpMessage(): void
     {
-        $list = new IPList();
+        $list = new IPList([
+            'Title' => 'Title',
+            'ProtectedRoutes' => 'routes'
+        ]);
         $fields = $list->getCMSFields();
 
         // IPHelpMessage should only appear if the list hasn't been saved yet, and should be replaced by the GridField
-        $this->assertTrue($fields->hasField('IPHelpMessage'));
+        $this->assertInstanceOf(LiteralField::class, $fields->fieldByName('IPHelpMessage'));
         $this->assertFalse($fields->hasField('IPs'));
 
         $list->write();
         $fields = $list->getCMSFields();
         $this->assertFalse($fields->hasField('IPHelpMessage'));
-        $this->assertTrue($fields->hasField('IPs'));
+        $this->assertInstanceOf(GridField::class, $fields->dataFieldByName('IPs'));
     }
 }
diff --git a/tests/Model/IPTest.php b/tests/Model/IPTest.php
index eb166a0..dd80cb2 100644
--- a/tests/Model/IPTest.php
+++ b/tests/Model/IPTest.php
@@ -7,7 +7,7 @@
 
 class IPTest extends SapphireTest
 {
-    public function testContainsIP()
+    public function testContainsIP(): void
     {
         $ip = new IP([
             'IP' => '10.1.1.1',
@@ -22,7 +22,7 @@ public function testContainsIP()
         $this->assertFalse($ip->contains('::1'));
     }
 
-    public function testContainsCIDR()
+    public function testContainsCIDR(): void
     {
         $ip = new IP([
             'IP' => '10.1.1.1/24',