diff --git a/src/AddToCampaignHandler.php b/src/AddToCampaignHandler.php
index 4e54b67..bf74549 100644
--- a/src/AddToCampaignHandler.php
+++ b/src/AddToCampaignHandler.php
@@ -92,7 +92,7 @@ public function __construct($controller = null, $data = [], $name = 'AddToCampai
     /**
      * Get what ChangeSets are available for an item to be added to by this user
      *
-     * @return ArrayList|ChangeSet[]
+     * @return ArrayList<ChangeSet>
      */
     protected function getAvailableChangeSets()
     {
@@ -111,7 +111,7 @@ protected function getAvailableChangeSets()
      * Get changesets that a given object is already in
      *
      * @param DataObject
-     * @return ArrayList[ChangeSet]
+     * @return ArrayList<ChangeSet>
      */
     protected function getInChangeSets($object)
     {
@@ -272,8 +272,6 @@ public function addToCampaign($object, $data): HTTPResponse
     {
         // Extract $campaignID from $data
         $campaignID = $this->getOrCreateCampaign($data);
-
-        /** @var ChangeSet $changeSet */
         $changeSet = ChangeSet::get()->byID($campaignID);
 
         if (!$changeSet) {
diff --git a/src/CampaignAdmin.php b/src/CampaignAdmin.php
index 51f693a..6d49fb5 100644
--- a/src/CampaignAdmin.php
+++ b/src/CampaignAdmin.php
@@ -246,7 +246,6 @@ protected function getListResource()
             ],
             '_embedded' => [$treeClass => []]
         ];
-        /** @var ChangeSet $item */
         foreach ($items as $item) {
             $sync = $this->shouldCampaignSync($item);
             $resource = $this->getChangeSetResource($item, $sync);
@@ -304,7 +303,6 @@ protected function getChangeSetResource(ChangeSet $changeSet, $sync = false)
                     continue;
                 }
 
-                /** @var ChangesetItem $changeSetItem */
                 $resource = $this->getChangeSetItemResource($changeSetItem);
                 if (!empty($resource)) {
                     $hal['_embedded']['items'][] = $resource;
@@ -406,7 +404,7 @@ protected function getChangeSetItemResource(ChangeSetItem $changeSetItem)
     /**
      * Gets viewable list of campaigns
      *
-     * @return SS_List
+     * @return SS_List<ChangeSet>
      */
     protected function getListItems()
     {
@@ -446,7 +444,6 @@ public function readCampaign(HTTPRequest $request)
                 return (new HTTPResponse(null, 400));
             }
 
-            /** @var ChangeSet $changeSet */
             $changeSet = ChangeSet::get()->filter('IsInferred', 0)->byID($request->param('ID'));
 
             if (!$changeSet) {
@@ -489,9 +486,7 @@ public function removeCampaignItem(HTTPRequest $request)
             return (new HTTPResponse(null, 400));
         }
 
-        /** @var ChangeSet $campaign */
         $campaign = ChangeSet::get()->byID($campaignID);
-        /** @var ChangeSetItem $item */
         $item = ChangeSetItem::get()->byID($itemID);
         if (!$campaign || !$item) {
             return (new HTTPResponse(null, 404));
@@ -558,7 +553,6 @@ public function publishCampaign(HTTPRequest $request)
             return (new HTTPResponse(null, 400));
         }
 
-        /** @var ChangeSet $changeSet */
         $changeSet = ChangeSet::get()->byID($id);
         if (!$changeSet) {
             return (new HTTPResponse(null, 404));
diff --git a/src/CampaignAdminExtension.php b/src/CampaignAdminExtension.php
index 3c8e54a..70ecbb5 100644
--- a/src/CampaignAdminExtension.php
+++ b/src/CampaignAdminExtension.php
@@ -2,9 +2,13 @@
 
 namespace SilverStripe\CampaignAdmin;
 
+use SilverStripe\Admin\LeftAndMain;
 use SilverStripe\Core\Extension;
 use SilverStripe\View\Requirements;
 
+/**
+ * @extends Extension<LeftAndMain>
+ */
 class CampaignAdminExtension extends Extension
 {
     public function init()
diff --git a/src/SiteTreeExtension.php b/src/SiteTreeExtension.php
index e19b9f2..0db5404 100644
--- a/src/SiteTreeExtension.php
+++ b/src/SiteTreeExtension.php
@@ -2,6 +2,7 @@
 
 namespace SilverStripe\CampaignAdmin;
 
+use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\Forms\FieldList;
 use SilverStripe\Forms\Tab;
 use SilverStripe\ORM\DataExtension;
@@ -9,6 +10,8 @@
 
 /**
  * Handles adding the "Add to Campaign" button to a page's secondary actions menu
+ *
+ * @extends DataExtension<SiteTree>
  */
 class SiteTreeExtension extends DataExtension
 {