diff --git a/lib/Constants.php b/lib/Constants.php
index d17c3c934..c71ca2ba3 100644
--- a/lib/Constants.php
+++ b/lib/Constants.php
@@ -119,6 +119,7 @@ class Constants {
 	public const ANSWER_TYPES_PREDEFINED = [
 		self::ANSWER_TYPE_DROPDOWN,
 		self::ANSWER_TYPE_LINEARSCALE,
+		self::ANSWER_TYPE_GRID,
 		self::ANSWER_TYPE_MULTIPLE,
 		self::ANSWER_TYPE_MULTIPLEUNIQUE,
 	];