diff --git a/src/Field.php b/src/Field.php
index 9e9cf04b..c140b995 100644
--- a/src/Field.php
+++ b/src/Field.php
@@ -145,6 +145,14 @@ public static function textPartLanguage(): array
             ->all();
     }
 
+    /**
+     * @inheritdoc
+     */
+    public static function phpType(): string
+    {
+        return sprintf('%s|null', FieldData::class);
+    }
+
     /**
      * Returns the nested element manager for a given CKEditor field.
      *