diff --git a/src/PhpFileRenderer/Item/RelationBlock.php b/src/PhpFileRenderer/Item/RelationBlock.php
index f84493a..57b4af2 100644
--- a/src/PhpFileRenderer/Item/RelationBlock.php
+++ b/src/PhpFileRenderer/Item/RelationBlock.php
@@ -14,6 +14,7 @@ class RelationBlock extends ArrayBlock
      * @see SchemaInterface
      */
     private const RELATION_SCHEMA_KEYS = [
+        'COLLECTION_TYPE',
         'MORPH_KEY',
         'CASCADE',
         'NULLABLE',