diff --git a/phpBB/phpbb/template/twig/extension.php b/phpBB/phpbb/template/twig/extension.php
index 7fde9e2cac..fa9fca0705 100644
--- a/phpBB/phpbb/template/twig/extension.php
+++ b/phpBB/phpbb/template/twig/extension.php
@@ -164,6 +164,7 @@ class extension extends \Twig\Extension\AbstractExtension
 		// We always include the last element (this was the past design)
 		$end = ($end == -1 || $end === null) ? null : $end + 1;
 
+		/** @psalm-suppress UndefinedFunction */
 		return twig_slice($env, $item, $start, $end, $preserveKeys);
 	}
 
@@ -213,6 +214,7 @@ class extension extends \Twig\Extension\AbstractExtension
 	{
 		$args = func_get_args();
 
+		/** @psalm-suppress UndefinedFunction */
 		return twig_escape_filter($this->environment, call_user_func_array([$this, 'lang'], $args), 'js');
 	}