diff --git a/src/StringTagField.php b/src/StringTagField.php
index 81abe03..d1786ff 100644
--- a/src/StringTagField.php
+++ b/src/StringTagField.php
@@ -6,6 +6,7 @@
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Core\Validation\ValidationResult;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\Validator;
 use SilverStripe\Model\List\ArrayList;
@@ -372,13 +373,11 @@ protected function getTags($term)
     /**
      * DropdownField assumes value will be a scalar so we must
      * override validate. This only applies to Silverstripe 3.2+
-     *
-     * @param Validator $validator
-     * @return bool
      */
-    public function validate($validator)
+    public function validate(): ValidationResult
     {
-        return $this->extendValidationResult(true, $validator);
+        // return $this->extendValidationResult(true, $validator);
+        return new ValidationResult;
     }
 
     /**
diff --git a/src/TagField.php b/src/TagField.php
index 317635c..4c57639 100644
--- a/src/TagField.php
+++ b/src/TagField.php
@@ -17,6 +17,7 @@
 use SilverStripe\ORM\Relation;
 use SilverStripe\Model\List\SS_List;
 use SilverStripe\Model\ArrayData;
+use SilverStripe\Core\Validation\ValidationResult;
 
 /**
  * Provides a tagging interface, storing links between tag DataObjects and a parent DataObject.
@@ -566,13 +567,12 @@ protected function getTags($term)
     /**
      * DropdownField assumes value will be a scalar so we must
      * override validate. This only applies to Silverstripe 3.2+
-     *
-     * @param Validator $validator
-     * @return bool
      */
-    public function validate($validator)
+    public function validate(): ValidationResult
     {
-        return $this->extendValidationResult(true, $validator);
+        // TODO: temporary code
+        return new ValidationResult;
+        // return $this->extendValidationResult(true, $validator);
     }
 
     /**