diff --git a/code/Forms/AssetFormFactory.php b/code/Forms/AssetFormFactory.php
index 7b3c68e77..1b0a7f267 100644
--- a/code/Forms/AssetFormFactory.php
+++ b/code/Forms/AssetFormFactory.php
@@ -92,7 +92,7 @@ public function getForm(RequestHandler $controller = null, $name = FormFactory::
             $form->loadDataFrom($record);
 
             // Mark as readonly for some types
-            if ($this->getFormType($context) === self::TYPE_ADMIN && !$record->canEdit()) {
+            if ($this->getFormType($context) === AssetFormFactory::TYPE_ADMIN && !$record->canEdit()) {
                 $form->makeReadonly();
             }
         }
@@ -242,7 +242,7 @@ protected function getFormFields(RequestHandler $controller = null, $formName, $
                 ->setRecordID($record->ID)
                 ->addExtraClass('editor__file-preview');
 
-            if ($this->getFormType($context) !== self::TYPE_ADMIN) {
+            if ($this->getFormType($context) !== AssetFormFactory::TYPE_ADMIN) {
                 $previewField->performReadonlyTransformation();
             }
 
diff --git a/code/Forms/MoveFormFactory.php b/code/Forms/MoveFormFactory.php
index 8488ca13d..42bdb3b0a 100644
--- a/code/Forms/MoveFormFactory.php
+++ b/code/Forms/MoveFormFactory.php
@@ -15,7 +15,7 @@ class MoveFormFactory implements FormFactory
 {
     use Extensible;
 
-    public function getForm(RequestHandler $controller = null, $name = self::DEFAULT_NAME, $context = [])
+    public function getForm(RequestHandler $controller = null, $name = MoveFormFactory::DEFAULT_NAME, $context = [])
     {
         $form = Form::create(
             $controller,
diff --git a/code/Forms/RemoteFileFormFactory.php b/code/Forms/RemoteFileFormFactory.php
index 1020149c2..8cc3070ce 100644
--- a/code/Forms/RemoteFileFormFactory.php
+++ b/code/Forms/RemoteFileFormFactory.php
@@ -92,7 +92,7 @@ class RemoteFileFormFactory implements FormFactory
      * @param array $context
      * @return Form
      */
-    public function getForm(RequestHandler $controller = null, $name = self::DEFAULT_NAME, $context = [])
+    public function getForm(RequestHandler $controller = null, $name = RemoteFileFormFactory::DEFAULT_NAME, $context = [])
     {
         // Allow form to be disabled
         if (!static::config()->get('enabled')) {
@@ -316,8 +316,8 @@ protected function getEditFormFields($context)
     protected function validateURLScheme($url)
     {
         $scheme = strtolower(parse_url($url ?? '', PHP_URL_SCHEME) ?? '');
-        $allowedSchemes = self::config()->get('fileurl_scheme_whitelist');
-        $disallowedSchemes = self::config()->get('fileurl_scheme_blacklist');
+        $allowedSchemes = static::config()->get('fileurl_scheme_whitelist');
+        $disallowedSchemes = static::config()->get('fileurl_scheme_blacklist');
         if (!$scheme
             || ($allowedSchemes && !in_array($scheme, $allowedSchemes ?? []))
             || ($disallowedSchemes && in_array($scheme, $disallowedSchemes ?? []))
@@ -336,8 +336,8 @@ protected function validateURLScheme($url)
     protected function validateURLHost($url)
     {
         $domain = strtolower(parse_url($url ?? '', PHP_URL_HOST) ?? '');
-        $allowedDomains = self::config()->get('fileurl_domain_whitelist');
-        $disallowedDomains = self::config()->get('fileurl_domain_blacklist');
+        $allowedDomains = static::config()->get('fileurl_domain_whitelist');
+        $disallowedDomains = static::config()->get('fileurl_domain_blacklist');
         if (!$domain
             || ($allowedDomains && !in_array($domain, $allowedDomains ?? []))
             || ($disallowedDomains && in_array($domain, $disallowedDomains ?? []))
@@ -359,8 +359,8 @@ protected function validateURLPort($url)
         if (!$port) {
             return;
         }
-        $allowedPorts = self::config()->get('fileurl_port_whitelist');
-        $disallowedPorts = self::config()->get('fileurl_port_blacklist');
+        $allowedPorts = static::config()->get('fileurl_port_whitelist');
+        $disallowedPorts = static::config()->get('fileurl_port_blacklist');
         if (($allowedPorts && !in_array($port, $allowedPorts ?? []))
             || ($disallowedPorts && in_array($port, $disallowedPorts ?? []))
         ) {
diff --git a/code/GraphQL/Resolvers/PublicationResolver.php b/code/GraphQL/Resolvers/PublicationResolver.php
index 5454a894d..e7aa2f25a 100644
--- a/code/GraphQL/Resolvers/PublicationResolver.php
+++ b/code/GraphQL/Resolvers/PublicationResolver.php
@@ -19,12 +19,12 @@ class PublicationResolver
 
     public static function resolvePublishFiles(...$params)
     {
-        return self::resolvePublicationOperation(self::ACTION_PUBLISH, ...$params);
+        return PublicationResolver::resolvePublicationOperation(PublicationResolver::ACTION_PUBLISH, ...$params);
     }
 
     public static function resolveUnpublishFiles(...$params)
     {
-        return self::resolvePublicationOperation(self::ACTION_UNPUBLISH, ...$params);
+        return PublicationResolver::resolvePublicationOperation(PublicationResolver::ACTION_UNPUBLISH, ...$params);
     }
 
     /**
@@ -45,7 +45,7 @@ private static function resolvePublicationOperation(
         if (!isset($args['ids']) || !is_array($args['ids'])) {
             throw new InvalidArgumentException('IDs must be an array');
         }
-        $isPublish = $action === self::ACTION_PUBLISH;
+        $isPublish = $action === PublicationResolver::ACTION_PUBLISH;
         $sourceStage = $isPublish ? Versioned::DRAFT : Versioned::LIVE;
         $force = $args['force'] ?? false;
         $quiet = $args['quiet'] ?? false;
@@ -87,8 +87,8 @@ private static function resolvePublicationOperation(
 
         foreach ($allowedFiles as $file) {
             $result[] = $isPublish
-                ? self::publishFile($file, $force)
-                : self::unpublishFile($file, $force);
+                ? PublicationResolver::publishFile($file, $force)
+                : PublicationResolver::unpublishFile($file, $force);
         }
 
         return $result;
@@ -116,7 +116,7 @@ private static function unpublishFile(File $file, $force = false)
     {
         // If not forcing, make sure we aren't interfering with any owners
         if (!$force) {
-            $ownersCount = self::countLiveOwners($file);
+            $ownersCount = PublicationResolver::countLiveOwners($file);
             if ($ownersCount) {
                 return new Notice(
                     _t(
diff --git a/code/Model/ThumbnailGenerator.php b/code/Model/ThumbnailGenerator.php
index 66225b5b1..29dc6b2e9 100644
--- a/code/Model/ThumbnailGenerator.php
+++ b/code/Model/ThumbnailGenerator.php
@@ -55,8 +55,8 @@ class ThumbnailGenerator
      * @var array
      */
     private static $thumbnail_links = [
-        AssetStore::VISIBILITY_PROTECTED => self::INLINE,
-        AssetStore::VISIBILITY_PUBLIC => self::URL,
+        AssetStore::VISIBILITY_PROTECTED => ThumbnailGenerator::INLINE,
+        AssetStore::VISIBILITY_PUBLIC => ThumbnailGenerator::URL,
     ];
 
     /**
@@ -141,9 +141,9 @@ public function generateLink(AssetContainer $thumbnail = null)
 
         // Build thumbnail
         switch ($urlRule) {
-            case self::URL:
+            case ThumbnailGenerator::URL:
                 return $thumbnail->getURL();
-            case self::INLINE:
+            case ThumbnailGenerator::INLINE:
                 // Generate inline content
                 $base64 = base64_encode($thumbnail->getString() ?? '');
                 return sprintf(
diff --git a/tests/php/Forms/FileFormBuilderTest/FileExtension.php b/tests/php/Forms/FileFormBuilderTest/FileExtension.php
index 0b6633d02..89dbde036 100644
--- a/tests/php/Forms/FileFormBuilderTest/FileExtension.php
+++ b/tests/php/Forms/FileFormBuilderTest/FileExtension.php
@@ -19,21 +19,21 @@ class FileExtension extends DataExtension implements TestOnly
 
     public function canDelete($member)
     {
-        return self::$canDelete;
+        return FileExtension::$canDelete;
     }
 
     public function canPublish($member = null)
     {
-        return self::$canPublish;
+        return FileExtension::$canPublish;
     }
 
     public function canUnpublish($member = null)
     {
-        return self::$canUnpublish;
+        return FileExtension::$canUnpublish;
     }
 
     public function canEdit($member = null)
     {
-        return self::$canEdit;
+        return FileExtension::$canEdit;
     }
 }
diff --git a/tests/php/Forms/RemoteFileFormFactoryTest/MockEmbed.php b/tests/php/Forms/RemoteFileFormFactoryTest/MockEmbed.php
index ffaa3f1a8..663a2320b 100644
--- a/tests/php/Forms/RemoteFileFormFactoryTest/MockEmbed.php
+++ b/tests/php/Forms/RemoteFileFormFactoryTest/MockEmbed.php
@@ -69,7 +69,7 @@ public function getOptions()
 
     /**
      * @param array $options
-     * @return self
+     * @return MockEmbed
      */
     public function setOptions(array $options)
     {