diff --git a/lib/public/Files/Template/Field.php b/lib/public/Files/Template/Field.php
index 628fef20a0a..c86a623f980 100644
--- a/lib/public/Files/Template/Field.php
+++ b/lib/public/Files/Template/Field.php
@@ -10,7 +10,7 @@ namespace OCP\Files\Template;
 use OCP\Files\Template\InvalidFieldTypeException;
 
 class Field implements \JsonSerializable {
-	private int $index;
+	private string $index;
 	private string $content;
 	private FieldType $type;
 	private ?int $id;