diff --git a/src/ORM/DataObject.php b/src/ORM/DataObject.php
index 8cbf4f9575d..08f99de6bf2 100644
--- a/src/ORM/DataObject.php
+++ b/src/ORM/DataObject.php
@@ -12,6 +12,7 @@
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Core\Resettable;
 use SilverStripe\Core\Validation\ValidationException;
+use SilverStripe\Core\Validation\ValidationInterface;
 use SilverStripe\Core\Validation\ValidationResult;
 use SilverStripe\Dev\Debug;
 use SilverStripe\Dev\Deprecation;
@@ -111,7 +112,7 @@
  * @property string $Created Date and time of DataObject creation.
  * @property string $ObsoleteClassName If ClassName no longer exists this will be set to the legacy value
  */
-class DataObject extends ModelData implements DataObjectInterface, i18nEntityProvider, Resettable
+class DataObject extends ModelData implements DataObjectInterface, i18nEntityProvider, Resettable, ValidationInterface
 {
     /**
      * Human-readable singular name.
@@ -1252,11 +1253,8 @@ public function forceChange()
      *
      * It is expected that you call validate() in your own application to test that an object is valid before
      * attempting a write, and respond appropriately if it isn't.
-     *
-     * @see {@link ValidationResult}
-     * @return ValidationResult
      */
-    public function validate()
+    public function validate(): ValidationResult
     {
         $result = ValidationResult::create();
         // Call DBField::validate() on every DBField
diff --git a/src/Security/Group.php b/src/Security/Group.php
index 4298c11dd89..6b5a59f1b6a 100755
--- a/src/Security/Group.php
+++ b/src/Security/Group.php
@@ -37,6 +37,7 @@
 use SilverStripe\ORM\Hierarchy\Hierarchy;
 use SilverStripe\ORM\ManyManyList;
 use SilverStripe\ORM\UnsavedRelationList;
+use SilverStripe\Core\Validation\ValidationResult;
 
 /**
  * A security group.
@@ -504,7 +505,7 @@ public function setCode($val)
         $this->setField('Code', Convert::raw2url($val));
     }
 
-    public function validate()
+    public function validate(): ValidationResult
     {
         $result = parent::validate();
 
diff --git a/src/Security/Member.php b/src/Security/Member.php
index 7707df74ee2..11eaa0273d7 100644
--- a/src/Security/Member.php
+++ b/src/Security/Member.php
@@ -1618,7 +1618,7 @@ public function canDelete($member = null)
     /**
      * Validate this member object.
      */
-    public function validate()
+    public function validate(): ValidationResult
     {
         // If validation is disabled, skip this step
         if (!DataObject::config()->uninherited('validation_enabled')) {
diff --git a/src/Security/PermissionRoleCode.php b/src/Security/PermissionRoleCode.php
index 8893382419e..2383e926838 100644
--- a/src/Security/PermissionRoleCode.php
+++ b/src/Security/PermissionRoleCode.php
@@ -4,6 +4,7 @@
 
 use SilverStripe\ORM\DataObject;
 use SilverStripe\Security\PermissionRole;
+use SilverStripe\Core\Validation\ValidationResult;
 
 /**
  * A PermissionRoleCode represents a single permission code assigned to a {@link PermissionRole}.
@@ -30,7 +31,7 @@ class PermissionRoleCode extends DataObject
         "Code" => true,
     ];
 
-    public function validate()
+    public function validate(): ValidationResult
     {
         $result = parent::validate();
 
diff --git a/tests/php/ORM/DataObjectTest/ValidatedObject.php b/tests/php/ORM/DataObjectTest/ValidatedObject.php
index 0912f8e7615..00b57b25fc6 100644
--- a/tests/php/ORM/DataObjectTest/ValidatedObject.php
+++ b/tests/php/ORM/DataObjectTest/ValidatedObject.php
@@ -14,7 +14,7 @@ class ValidatedObject extends DataObject implements TestOnly
         'Name' => 'Varchar(50)'
     ];
 
-    public function validate()
+    public function validate(): ValidationResult
     {
         $result = ValidationResult::create();
         if (empty($this->Name)) {