diff --git a/src/AuditCommand.php b/src/AuditCommand.php
index b07e44b..a4ae641 100644
--- a/src/AuditCommand.php
+++ b/src/AuditCommand.php
@@ -309,7 +309,7 @@ private static function clearLine(OutputInterface $output): void
      */
     private static function isUnderTest(): bool
     {
-        $value = filter_var(getenv('COMPOSER_AUDIT_TEST'), \FILTER_VALIDATE_BOOL);
+        $value = filter_var(getenv('COMPOSER_AUDIT_TEST'), \FILTER_VALIDATE_BOOLEAN);
 
         return $value !== null ? $value : false;
     }