diff --git a/code/BasicFieldsTestFileExtension.php b/code/BasicFieldsTestFileExtension.php
index 8bf7b06..874728a 100644
--- a/code/BasicFieldsTestFileExtension.php
+++ b/code/BasicFieldsTestFileExtension.php
@@ -1,8 +1,8 @@
 <?php
 
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 
-class BasicFieldsTestFileExtension extends DataExtension
+class BasicFieldsTestFileExtension extends Extension
 {
     private static $has_one = [
         'TestPage' => BasicFieldsTestPage::class,
diff --git a/code/DevBuildGeneratorExtension.php b/code/DevBuildGeneratorExtension.php
index 9d5dada..94070b1 100644
--- a/code/DevBuildGeneratorExtension.php
+++ b/code/DevBuildGeneratorExtension.php
@@ -1,12 +1,12 @@
 <?php
 
 use SilverStripe\Core\Config\Configurable;
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 
 /**
  * There is no good place to put this setting, so it gets a class.
  */
-class DevBuildGeneratorExtension extends DataExtension
+class DevBuildGeneratorExtension extends Extension
 {
     use Configurable;
 
diff --git a/code/FileUploadRole.php b/code/FileUploadRole.php
index 64e59d8..ff40d9f 100644
--- a/code/FileUploadRole.php
+++ b/code/FileUploadRole.php
@@ -1,7 +1,8 @@
 <?php
 
-use SilverStripe\ORM\DataExtension;
-class FileUploadRole extends DataExtension
+use SilverStripe\Core\Extension;
+
+class FileUploadRole extends Extension
 {
     private static $has_one = array(
         'AFile' => 'SilverStripe\\Assets\\File',
diff --git a/code/FrameworkTestFileExtension.php b/code/FrameworkTestFileExtension.php
index 808170a..dc8bcc7 100644
--- a/code/FrameworkTestFileExtension.php
+++ b/code/FrameworkTestFileExtension.php
@@ -1,7 +1,8 @@
 <?php
 
-use SilverStripe\ORM\DataExtension;
-class FrameworkTestFileExtension extends DataExtension
+use SilverStripe\Core\Extension;
+
+class FrameworkTestFileExtension extends Extension
 {
     private static $has_one = array(
         'Company' => 'SilverStripe\\FrameworkTest\\Model\\Company',
diff --git a/code/FrameworkTestModelAdminExtension.php b/code/FrameworkTestModelAdminExtension.php
index 10f5147..6a1e3ce 100644
--- a/code/FrameworkTestModelAdminExtension.php
+++ b/code/FrameworkTestModelAdminExtension.php
@@ -1,8 +1,8 @@
 <?php
 
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 
-class FrameworkTestModelAdminExtension extends DataExtension
+class FrameworkTestModelAdminExtension extends Extension
 {
     private static $page_length = 3;
 }
diff --git a/code/FrameworkTestRole.php b/code/FrameworkTestRole.php
index b838d43..21ca36e 100644
--- a/code/FrameworkTestRole.php
+++ b/code/FrameworkTestRole.php
@@ -2,14 +2,12 @@
 
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DB;
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 use SilverStripe\Security\Member;
 use SilverStripe\Forms\FieldList;
 use SilverStripe\Forms\TreeDropdownField;
 
-
-
-class FrameworkTestRole extends DataExtension
+class FrameworkTestRole extends Extension
 {
 
     private static $has_one = array(
diff --git a/code/FrameworkTestSiteTreeExtension.php b/code/FrameworkTestSiteTreeExtension.php
index 846b840..460ab64 100644
--- a/code/FrameworkTestSiteTreeExtension.php
+++ b/code/FrameworkTestSiteTreeExtension.php
@@ -1,7 +1,8 @@
 <?php
 
-use SilverStripe\ORM\DataExtension;
-class FrameworkTestSiteTreeExtension extends DataExtension
+use SilverStripe\Core\Extension;
+
+class FrameworkTestSiteTreeExtension extends Extension
 {
     private static $has_one = array('RelationFieldsTestPage' => 'RelationFieldsTestPage');
     private static $belongs_many_many = array('RelationFieldsTestPages' => 'RelationFieldsTestPage');
diff --git a/code/TestDataObjectExtension.php b/code/TestDataObjectExtension.php
index c1346c8..ece8603 100644
--- a/code/TestDataObjectExtension.php
+++ b/code/TestDataObjectExtension.php
@@ -2,11 +2,11 @@
 
 namespace SilverStripe\FrameworkTest\Extension;
 
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 use SilverStripe\Security\Permission;
 use SilverStripe\Security\PermissionProvider;
 
-class TestDataObjectExtension extends DataExtension implements PermissionProvider
+class TestDataObjectExtension extends Extension implements PermissionProvider
 {
     public function providePermissions()
     {
diff --git a/code/elemental/ElementalBehatTestExtension.php b/code/elemental/ElementalBehatTestExtension.php
index 80ca356..02a33e3 100644
--- a/code/elemental/ElementalBehatTestExtension.php
+++ b/code/elemental/ElementalBehatTestExtension.php
@@ -3,9 +3,9 @@
 namespace SilverStripe\FrameworkTest\Elemental\Extension;
 
 use DNADesign\Elemental\Models\ElementalArea;
-use SilverStripe\ORM\DataExtension;
+use SilverStripe\Core\Extension;
 
-class ElementalBehatTestExtension extends DataExtension
+class ElementalBehatTestExtension extends Extension
 {
     private static $has_one = [
         'ElementalArea' => ElementalArea::class,