diff --git a/code/Control/UserDefinedFormAdmin.php b/code/Control/UserDefinedFormAdmin.php
index 7cc75c2..b61a003 100644
--- a/code/Control/UserDefinedFormAdmin.php
+++ b/code/Control/UserDefinedFormAdmin.php
@@ -297,7 +297,7 @@ class UserDefinedFormAdmin extends LeftAndMain
     private static function updateFormSubmissionFolderPermissions()
     {
         // ensure the FormSubmissions folder is only accessible to Administrators
-        $formSubmissionsFolder = Folder::find(self::config()->get('form_submissions_folder'));
+        $formSubmissionsFolder = Folder::find(static::config()->get('form_submissions_folder'));
         $formSubmissionsFolder->CanViewType = InheritedPermissions::ONLY_THESE_USERS;
         $formSubmissionsFolder->ViewerGroups()->removeAll();
         $formSubmissionsFolder->ViewerGroups()->add(Group::get_one(Group::class, ['"Code"' => 'administrators']));
@@ -314,16 +314,16 @@ class UserDefinedFormAdmin extends LeftAndMain
      */
     public static function getFormSubmissionFolder(string $subFolder = null): ?Folder
     {
-        $folderPath = self::config()->get('form_submissions_folder');
+        $folderPath = static::config()->get('form_submissions_folder');
         if ($subFolder) {
             $folderPath .= '/' . $subFolder;
         }
-        $formSubmissionsFolderExists = !!Folder::find(self::config()->get('form_submissions_folder'));
+        $formSubmissionsFolderExists = !!Folder::find(static::config()->get('form_submissions_folder'));
         $folder = Folder::find_or_make($folderPath);
 
         // Set default permissions if this is the first time we create the form submission folder
         if (!$formSubmissionsFolderExists) {
-            self::updateFormSubmissionFolderPermissions();
+            UserDefinedFormAdmin::updateFormSubmissionFolderPermissions();
             // Make sure we return the folder with the latest permission
             $folder = Folder::find($folderPath);
         }
diff --git a/code/Control/UserDefinedFormController.php b/code/Control/UserDefinedFormController.php
index 3837690..be8df35 100644
--- a/code/Control/UserDefinedFormController.php
+++ b/code/Control/UserDefinedFormController.php
@@ -59,7 +59,7 @@ class UserDefinedFormController extends PageController
     /**
      * Size that an uploaded file must not excede for it to be attached to an email
      * Follows PHP "shorthand bytes" definition rules.
-     * @see self::parseByteSizeString()
+     * @see UserDefinedFormController::parseByteSizeString()
      *
      * @var int
      * @config
@@ -314,7 +314,7 @@ JS
                         }
 
                         $file = Versioned::withVersionedMode(function () use ($field, $form) {
-                            $stage = Injector::inst()->get(self::class)->config()->get('file_upload_stage');
+                            $stage = Injector::inst()->get(UserDefinedFormController::class)->config()->get('file_upload_stage');
                             Versioned::set_stage($stage);
 
                             $foldername = $field->getFormField()->getFolderName();
diff --git a/code/Extension/UserFormFileExtension.php b/code/Extension/UserFormFileExtension.php
index 82f5a60..a924405 100644
--- a/code/Extension/UserFormFileExtension.php
+++ b/code/Extension/UserFormFileExtension.php
@@ -47,8 +47,8 @@ class UserFormFileExtension extends DataExtension
     public function updateTrackedFormUpload(&$value): void
     {
         $file = $this->owner;
-        if ($file->UserFormUpload != self::USER_FORM_UPLOAD_UNKNOWN) {
-            $value = $file->UserFormUpload == self::USER_FORM_UPLOAD_TRUE;
+        if ($file->UserFormUpload != UserFormFileExtension::USER_FORM_UPLOAD_UNKNOWN) {
+            $value = $file->UserFormUpload == UserFormFileExtension::USER_FORM_UPLOAD_TRUE;
             return;
         }
         if ($file->ClassName == Folder::class) {
@@ -71,7 +71,7 @@ class UserFormFileExtension extends DataExtension
         }
         $tableName = Convert::raw2sql(DataObject::getSchema()->tableName(File::class));
         $column = 'UserFormUpload';
-        $enumVal = $value ? self::USER_FORM_UPLOAD_TRUE : self::USER_FORM_UPLOAD_FALSE;
+        $enumVal = $value ? UserFormFileExtension::USER_FORM_UPLOAD_TRUE : UserFormFileExtension::USER_FORM_UPLOAD_FALSE;
         SQLUpdate::create()
             ->setTable(sprintf('"%s"', $tableName))
             ->addWhere(['"ID" = ?' => [$this->owner->ID]])
diff --git a/code/Model/EditableFormField.php b/code/Model/EditableFormField.php
index 08d2dd2..e9f3af4 100755
--- a/code/Model/EditableFormField.php
+++ b/code/Model/EditableFormField.php
@@ -281,9 +281,9 @@ class EditableFormField extends DataObject
         $fields->fieldByName('Root.Main')->setTitle(_t('SilverStripe\\CMS\\Model\\SiteTree.TABMAIN', 'Main'));
 
         // Custom settings
-        if (!empty(self::$allowed_css)) {
+        if (!empty(EditableFormField::$allowed_css)) {
             $cssList = [];
-            foreach (self::$allowed_css as $k => $v) {
+            foreach (EditableFormField::$allowed_css as $k => $v) {
                 if (!is_array($v)) {
                     $cssList[$k]=$v;
                 } elseif ($k === $this->ClassName) {
@@ -351,7 +351,7 @@ class EditableFormField extends DataObject
 
         // make sure to migrate the class across (prior to v5.x)
         DB::query("UPDATE \"EditableFormField\" SET \"ParentClass\" = 'Page' WHERE \"ParentClass\" IS NULL");
-        if (self::has_extension(Versioned::class)) {
+        if (EditableFormField::has_extension(Versioned::class)) {
             DB::query("UPDATE \"EditableFormField_Live\" SET \"ParentClass\" = 'Page' WHERE \"ParentClass\" IS NULL");
             DB::query("UPDATE \"EditableFormField_Versions\" SET \"ParentClass\" = 'Page' WHERE \"ParentClass\" IS NULL");
         }
@@ -602,7 +602,7 @@ class EditableFormField extends DataObject
     {
         if (is_array($allowed)) {
             foreach ($allowed as $k => $v) {
-                self::$allowed_css[$k] = (!is_null($v)) ? $v : $k;
+                EditableFormField::$allowed_css[$k] = (!is_null($v)) ? $v : $k;
             }
         }
     }
diff --git a/code/Model/EditableFormField/EditableOption.php b/code/Model/EditableFormField/EditableOption.php
index 944e368..dce01ce 100644
--- a/code/Model/EditableFormField/EditableOption.php
+++ b/code/Model/EditableFormField/EditableOption.php
@@ -55,7 +55,7 @@ class EditableOption extends DataObject
      */
     public static function allow_empty_values()
     {
-        return (bool) self::$allow_empty_values;
+        return (bool) EditableOption::$allow_empty_values;
     }
 
     /**
@@ -65,7 +65,7 @@ class EditableOption extends DataObject
      */
     public static function set_allow_empty_values($allow)
     {
-        self::$allow_empty_values = (bool) $allow;
+        EditableOption::$allow_empty_values = (bool) $allow;
     }
 
     /**
@@ -77,7 +77,7 @@ class EditableOption extends DataObject
     public function getValue()
     {
         $value = $this->getField('Value');
-        if (empty($value) && !self::allow_empty_values()) {
+        if (empty($value) && !EditableOption::allow_empty_values()) {
             return $this->Title;
         }
         return $value;