diff --git a/README.md b/README.md
index c0e6212..88f73f4 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 ## Installation (with composer)
 
     $ composer require heyday/silverstripe-abtesting:~0.1
+    
+    For 2.4 see the tag 0.1.7
 
 ## Usage
 
diff --git a/code/ABTestingConfigExtension.php b/code/ABTestingConfigExtension.php
index 0550c73..e13bdb7 100644
--- a/code/ABTestingConfigExtension.php
+++ b/code/ABTestingConfigExtension.php
@@ -3,30 +3,20 @@
 /**
  * Class ABTestingConfigExtension
  */
-class ABTestingConfigExtension extends Extension
+class ABTestingConfigExtension extends DataExtension
 {
 
-    /**
-     * Required for DataObject extensions
-     *
-     * @return array
-     */
-    public function extraStatics()
-    {
-        return array(
-            'db' => array(
-                'ABGlobalTest' => 'Boolean',
-                'ABTestGlobalScript' => 'Text'
-            )
-        );
-    }
+    public static $db = array(
+        'ABGlobalTest' => 'Boolean',
+        'ABTestGlobalScript' => 'Text'
+    );
 
     /**
      * Update the CMS fields on the extended object
      *
-     * @param FieldSet $fields
+     * @param FieldList $fields
      */
-    public function updateCMSFields(FieldSet &$fields)
+    public function updateCMSFields(FieldList $fields)
     {
 
         $member = Member::currentUser();
diff --git a/code/ABTestingExtension.php b/code/ABTestingExtension.php
index 9167684..fe8418e 100644
--- a/code/ABTestingExtension.php
+++ b/code/ABTestingExtension.php
@@ -3,19 +3,9 @@
 /**
  * Class ABTestingExtension
  */
-class ABTestingExtension extends Extension
+class ABTestingExtension extends DataExtension
 {
 
-    /**
-     * Required for DataObject extensions
-     *
-     * @return array
-     */
-    public function extraStatics()
-    {
-        return array();
-    }
-
     /**
      * @var array
      */
diff --git a/code/ABTestingPageExtension.php b/code/ABTestingPageExtension.php
index 612f868..00c46d1 100644
--- a/code/ABTestingPageExtension.php
+++ b/code/ABTestingPageExtension.php
@@ -3,30 +3,20 @@
 /**
  * Class ABTestingPageExtension
  */
-class ABTestingPageExtension extends Extension
+class ABTestingPageExtension extends DataExtension
 {
 
-    /**
-     * Required for DataObject extensions
-     *
-     * @return array
-     */
-    public function extraStatics()
-    {
-        return array(
-            'db' => array(
-                'ABTestPage' => 'Boolean',
-                'ABTestInlineScript' => 'Text'
-            )
-        );
-    }
+    public static $db = array(
+        'ABTestPage' => 'Boolean',
+        'ABTestInlineScript' => 'Text'
+    );
 
     /**
      * Update the CMS fields on the extended object
      *
-     * @param FieldSet $fields
+     * @param FieldList $fields
      */
-    public function updateCMSFields(FieldSet &$fields)
+    public function updateCMSFields(FieldList $fields)
     {
 
         $member = Member::currentUser();